diff --git a/.bumpversion.cfg b/.bumpversion.cfg
new file mode 100644
index 0000000..e994796
--- /dev/null
+++ b/.bumpversion.cfg
@@ -0,0 +1,8 @@
+[bumpversion]
+current_version = 0.3.6
+commit = True
+tag = True
+tag_name = {new_version}
+
+[bumpversion:file:setup.py]
+parse = version\s*=\s*['"](?P<major>\d+)\.(?P<minor>\d+)\.(?P<patch>\d+)
\ No newline at end of file
diff --git a/.flake8 b/.flake8
new file mode 100644
index 0000000..7062cb6
--- /dev/null
+++ b/.flake8
@@ -0,0 +1,30 @@
+[flake8]
+max-line-length = 119
+per-file-ignores =
+# Exclude files that are meant to provide top-level imports
+# E402: Module level import not at top of file
+# F401: Module imported but unused
+    sklearn_crfsuite/__init__.py:E402
+
+# Issues pending a review:
+ignore =
+    B017,
+    D100,
+    D101,
+    D102,
+    D103,
+    D104,
+    D105,
+    D107,
+    D200,
+    D205,
+    D400,
+    E203,
+    E501,
+    E701,
+    E704,
+    F401,
+    W503
+exclude =
+    docs/conf.py
+    setup.py
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
new file mode 100644
index 0000000..203d495
--- /dev/null
+++ b/.github/workflows/publish.yml
@@ -0,0 +1,22 @@
+name: publish
+on:
+  push:
+    tags:
+      - "[0-9]+.[0-9]+.[0-9]+"
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: '3.12'
+    - name: Install dependencies
+      run: |
+        pip install --upgrade build twine
+        python -m build
+    - name: Publish to PyPI
+      uses: pypa/gh-action-pypi-publish@v1.8.14
+      with:
+        password: ${{ secrets.PYPI_TOKEN }}
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..7a3424a
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,53 @@
+name: tox
+on:
+  pull_request:
+  push:
+    branches: [ main ]
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+        - python-version: "3.8"
+        - python-version: "3.9"
+        - python-version: "3.10"
+        - python-version: "3.11"
+        - python-version: "3.12"
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v5
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        python -m pip install tox
+    - name: tox
+      run: |
+        tox -e ${{ matrix.toxenv || 'py' }}
+    - name: coverage
+      if: ${{ success() }}
+      run: bash <(curl -s https://codecov.io/bash)
+  check:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ['3.12']
+        tox-job: ["pre-commit", "mypy", "twinecheck"]
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v5
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        python -m pip install tox
+    - name: tox
+      run: |
+        tox -e ${{ matrix.tox-job }}
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 0000000..83e03b0
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,26 @@
+default_language_version:
+  python: python3
+repos:
+- hooks:
+  - id: black
+  repo: https://github.com/ambv/black
+  rev: 24.3.0
+- hooks:
+  - id: isort
+  repo: https://github.com/PyCQA/isort
+  rev: 5.13.2
+- hooks:
+  - id: flake8
+    additional_dependencies:
+    - flake8-bugbear
+    - flake8-comprehensions
+    - flake8-debugger
+    - flake8-docstrings
+    - flake8-string-format
+  repo: https://github.com/pycqa/flake8
+  rev: 7.0.0
+- repo: https://github.com/asottile/pyupgrade
+  rev: v3.15.2
+  hooks:
+  - id: pyupgrade
+    args: [--py38-plus, --keep-runtime-typing]
diff --git a/docs/conf.py b/docs/conf.py
index 7c94736..2eb78cf 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python3
-# -*- coding: utf-8 -*-
 #
 # sklearn-crfsuite documentation build configuration file, created by
 # sphinx-quickstart on Fri Nov 27 03:50:38 2015.
@@ -13,103 +12,106 @@
 # All configuration values have a default; values that are commented out
 # serve to show the default.
 
-import sys
 import os
 import shlex
+import sys
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.
-sys.path.insert(0, os.path.abspath('..'))
+sys.path.insert(0, os.path.abspath(".."))
 
 
 from unittest.mock import MagicMock
 
+
 class Mock(MagicMock):
     @classmethod
     def __getattr__(cls, name):
         return MagicMock()
 
-MOCK_MODULES = ['sklearn', 'sklearn.metrics', 'tqdm', 'tabulate', 'numpy',
-                'pycrfsuite']
+
+MOCK_MODULES = ["sklearn", "sklearn.metrics", "tqdm", "tabulate", "numpy", "pycrfsuite"]
 sys.modules.update((mod_name, Mock()) for mod_name in MOCK_MODULES)
 
 # -- General configuration ------------------------------------------------
 
 # If your documentation needs a minimal Sphinx version, state it here.
-#needs_sphinx = '1.0'
+# needs_sphinx = '1.0'
 
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
 extensions = [
-    'sphinx.ext.autodoc',
-    'sphinx.ext.viewcode',
-    'sphinx.ext.napoleon',
-    'sphinx.ext.mathjax',
+    "IPython.sphinxext.ipython_console_highlighting",
+    "IPython.sphinxext.ipython_directive",
+    "sphinx.ext.autodoc",
+    "sphinx.ext.viewcode",
+    "sphinx.ext.napoleon",
+    "sphinx.ext.mathjax",
 ]
 numpydoc_show_class_members = False
-autodoc_member_order = 'bysource'
+autodoc_member_order = "bysource"
 
 # Add any paths that contain templates here, relative to this directory.
-templates_path = ['_templates']
+templates_path = ["_templates"]
 
 # The suffix(es) of source filenames.
 # You can specify multiple suffix as a list of string:
 # source_suffix = ['.rst', '.md']
-source_suffix = '.rst'
+source_suffix = ".rst"
 
 # The master toctree document.
-master_doc = 'index'
+master_doc = "index"
 
 # General information about the project.
-project = 'sklearn-crfsuite'
-copyright = '2015, Mikhail Korobov'
-author = 'Mikhail Korobov'
+project = "sklearn-crfsuite"
+copyright = "Mikhail Korobov"
+author = "Mikhail Korobov"
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
 #
 # The short X.Y version.
-version = '0.3'
+version = "0.3"
 # The full version, including alpha/beta/rc tags.
-release = '0.3'
+release = "0.3"
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = "en"
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
-exclude_patterns = ['_build', 'CoNLL2002.rst']
+exclude_patterns = ["_build", "CoNLL2002.rst"]
 
 # The reST default role (used for this markup: `text`) to use for all
 # documents.
-#default_role = None
+# default_role = None
 
 # If true, '()' will be appended to :func: etc. cross-reference text.
-#add_function_parentheses = True
+# add_function_parentheses = True
 
 # If true, the current module name will be prepended to all description
 # unit titles (such as .. function::).
-#add_module_names = True
+# add_module_names = True
 
 # If true, sectionauthor and moduleauthor directives will be shown in the
 # output. They are ignored by default.
-#show_authors = False
+# show_authors = False
 
 # The name of the Pygments (syntax highlighting) style to use.
-pygments_style = 'sphinx'
+pygments_style = "sphinx"
 
 # A list of ignored prefixes for module index sorting.
-#modindex_common_prefix = []
+# modindex_common_prefix = []
 
 # If true, keep warnings as "system message" paragraphs in the built documents.
-#keep_warnings = False
+# keep_warnings = False
 
 # If true, `todo` and `todoList` produce output, else they produce nothing.
 todo_include_todos = False
@@ -127,135 +129,137 @@ def __getattr__(cls, name):
 
 
 # Add any paths that contain custom themes here, relative to this directory.
-#html_theme_path = []
+# html_theme_path = []
 
 # The name for this set of Sphinx documents.  If None, it defaults to
 # "<project> v<release> documentation".
-#html_title = None
+# html_title = None
 
 # A shorter title for the navigation bar.  Default is the same as html_title.
-#html_short_title = None
+# html_short_title = None
 
 # The name of an image file (relative to this directory) to place at the top
 # of the sidebar.
-#html_logo = None
+# html_logo = None
 
 # The name of an image file (within the static path) to use as favicon of the
 # docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
 # pixels large.
-#html_favicon = None
+# html_favicon = None
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
-html_static_path = ['_static']
+# html_static_path = ["_static"]
 
 # Add any extra paths that contain custom files (such as robots.txt or
 # .htaccess) here, relative to this directory. These files are copied
 # directly to the root of the documentation.
-#html_extra_path = []
+# html_extra_path = []
 
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.
-#html_last_updated_fmt = '%b %d, %Y'
+# html_last_updated_fmt = '%b %d, %Y'
 
 # If true, SmartyPants will be used to convert quotes and dashes to
 # typographically correct entities.
-#html_use_smartypants = True
+# html_use_smartypants = True
 
 # Custom sidebar templates, maps document names to template names.
-#html_sidebars = {}
+# html_sidebars = {}
 
 # Additional templates that should be rendered to pages, maps page names to
 # template names.
-#html_additional_pages = {}
+# html_additional_pages = {}
 
 # If false, no module index is generated.
-#html_domain_indices = True
+# html_domain_indices = True
 
 # If false, no index is generated.
-#html_use_index = True
+# html_use_index = True
 
 # If true, the index is split into individual pages for each letter.
-#html_split_index = False
+# html_split_index = False
 
 # If true, links to the reST sources are added to the pages.
-#html_show_sourcelink = True
+# html_show_sourcelink = True
 
 # If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
-#html_show_sphinx = True
+# html_show_sphinx = True
 
 # If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
-#html_show_copyright = True
+# html_show_copyright = True
 
 # If true, an OpenSearch description file will be output, and all pages will
 # contain a <link> tag referring to it.  The value of this option must be the
 # base URL from which the finished HTML is served.
-#html_use_opensearch = ''
+# html_use_opensearch = ''
 
 # This is the file name suffix for HTML files (e.g. ".xhtml").
-#html_file_suffix = None
+# html_file_suffix = None
 
 # Language to be used for generating the HTML full-text search index.
 # Sphinx supports the following languages:
 #   'da', 'de', 'en', 'es', 'fi', 'fr', 'h', 'it', 'ja'
 #   'nl', 'no', 'pt', 'ro', 'r', 'sv', 'tr'
-#html_search_language = 'en'
+# html_search_language = 'en'
 
 # A dictionary with options for the search language support, empty by default.
 # Now only 'ja' uses this config value
-#html_search_options = {'type': 'default'}
+# html_search_options = {'type': 'default'}
 
 # The name of a javascript file (relative to the configuration directory) that
 # implements a search results scorer. If empty, the default will be used.
-#html_search_scorer = 'scorer.js'
+# html_search_scorer = 'scorer.js'
 
 # Output file base name for HTML help builder.
-htmlhelp_basename = 'sklearn-crfsuitedoc'
+htmlhelp_basename = "sklearn-crfsuitedoc"
 
 # -- Options for LaTeX output ---------------------------------------------
 
 latex_elements = {
-# The paper size ('letterpaper' or 'a4paper').
-#'papersize': 'letterpaper',
-
-# The font size ('10pt', '11pt' or '12pt').
-#'pointsize': '10pt',
-
-# Additional stuff for the LaTeX preamble.
-#'preamble': '',
-
-# Latex figure (float) alignment
-#'figure_align': 'htbp',
+    # The paper size ('letterpaper' or 'a4paper').
+    #'papersize': 'letterpaper',
+    # The font size ('10pt', '11pt' or '12pt').
+    #'pointsize': '10pt',
+    # Additional stuff for the LaTeX preamble.
+    #'preamble': '',
+    # Latex figure (float) alignment
+    #'figure_align': 'htbp',
 }
 
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title,
 #  author, documentclass [howto, manual, or own class]).
 latex_documents = [
-  (master_doc, 'sklearn-crfsuite.tex', 'sklearn-crfsuite Documentation',
-   'Mikhail Korobov', 'manual'),
+    (
+        master_doc,
+        "sklearn-crfsuite.tex",
+        "sklearn-crfsuite Documentation",
+        "Mikhail Korobov",
+        "manual",
+    ),
 ]
 
 # The name of an image file (relative to this directory) to place at the top of
 # the title page.
-#latex_logo = None
+# latex_logo = None
 
 # For "manual" documents, if this is true, then toplevel headings are parts,
 # not chapters.
-#latex_use_parts = False
+# latex_use_parts = False
 
 # If true, show page references after internal links.
-#latex_show_pagerefs = False
+# latex_show_pagerefs = False
 
 # If true, show URL addresses after external links.
-#latex_show_urls = False
+# latex_show_urls = False
 
 # Documents to append as an appendix to all manuals.
-#latex_appendices = []
+# latex_appendices = []
 
 # If false, no module index is generated.
-#latex_domain_indices = True
+# latex_domain_indices = True
 
 
 # -- Options for manual page output ---------------------------------------
@@ -263,12 +267,11 @@ def __getattr__(cls, name):
 # One entry per manual page. List of tuples
 # (source start file, name, description, authors, manual section).
 man_pages = [
-    (master_doc, 'sklearn-crfsuite', 'sklearn-crfsuite Documentation',
-     [author], 1)
+    (master_doc, "sklearn-crfsuite", "sklearn-crfsuite Documentation", [author], 1)
 ]
 
 # If true, show URL addresses after external links.
-#man_show_urls = False
+# man_show_urls = False
 
 
 # -- Options for Texinfo output -------------------------------------------
@@ -277,19 +280,25 @@ def __getattr__(cls, name):
 # (source start file, target name, title, author,
 #  dir menu entry, description, category)
 texinfo_documents = [
-  (master_doc, 'sklearn-crfsuite', 'sklearn-crfsuite Documentation',
-   author, 'sklearn-crfsuite', 'One line description of project.',
-   'Miscellaneous'),
+    (
+        master_doc,
+        "sklearn-crfsuite",
+        "sklearn-crfsuite Documentation",
+        author,
+        "sklearn-crfsuite",
+        "One line description of project.",
+        "Miscellaneous",
+    ),
 ]
 
 # Documents to append as an appendix to all manuals.
-#texinfo_appendices = []
+# texinfo_appendices = []
 
 # If false, no module index is generated.
-#texinfo_domain_indices = True
+# texinfo_domain_indices = True
 
 # How to display URL addresses: 'footnote', 'no', or 'inline'.
-#texinfo_show_urls = 'footnote'
+# texinfo_show_urls = 'footnote'
 
 # If true, do not generate a @detailmenu in the "Top" node's menu.
-#texinfo_no_detailmenu = False
+# texinfo_no_detailmenu = False
diff --git a/docs/requirements.txt b/docs/requirements.txt
new file mode 100644
index 0000000..499a35d
--- /dev/null
+++ b/docs/requirements.txt
@@ -0,0 +1,6 @@
+ipython
+matplotlib
+numpy
+pickleshare  # ipython optional dependency
+sphinx==6.2.1
+sphinx-rtd-theme==2.0.0
diff --git a/setup.py b/setup.py
index c454d67..02724c7 100755
--- a/setup.py
+++ b/setup.py
@@ -2,33 +2,34 @@
 from setuptools import setup
 
 setup(
-    name='sklearn-crfsuite',
-    version='0.3.6',
-    author='Mikhail Korobov',
-    author_email='kmike84@gmail.com',
-    license='MIT license',
-    long_description=open('README.rst').read() + "\n\n" + open('CHANGES.rst').read(),
+    name="sklearn-crfsuite",
+    version="0.3.6",
+    author="Mikhail Korobov",
+    author_email="kmike84@gmail.com",
+    license="MIT license",
+    long_description=open("README.rst").read() + "\n\n" + open("CHANGES.rst").read(),
+    long_description_content_type="text/x-rst",
     description="CRFsuite (python-crfsuite) wrapper which provides interface simlar to scikit-learn",
-    url='https://github.com/TeamHG-Memex/sklearn-crfsuite',
+    url="https://github.com/TeamHG-Memex/sklearn-crfsuite",
     zip_safe=False,
-    packages=['sklearn_crfsuite'],
+    packages=["sklearn_crfsuite"],
     install_requires=[
+        "python-crfsuite >= 0.9.7",
+        "scikit-learn >= 0.24.0",
+        "tabulate >= 0.4.2",
         "tqdm >= 2.0",
-        "six",
-        "tabulate",
-        "python-crfsuite >= 0.8.3"
     ],
     classifiers=[
-        'Development Status :: 3 - Alpha',
-        'License :: OSI Approved :: MIT License',
-        'Intended Audience :: Developers',
-        'Operating System :: OS Independent',
-        'Programming Language :: Python',
-        'Programming Language :: Python :: 2',
-        'Programming Language :: Python :: 2.7',
-        'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.4',
-        'Programming Language :: Python :: 3.5',
-        'Programming Language :: Python :: 3.6',
+        "Development Status :: 3 - Alpha",
+        "License :: OSI Approved :: MIT License",
+        "Intended Audience :: Developers",
+        "Operating System :: OS Independent",
+        "Programming Language :: Python",
+        "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
+        "Programming Language :: Python :: 3.11",
+        "Programming Language :: Python :: 3.12",
     ],
 )
diff --git a/sklearn_crfsuite/__init__.py b/sklearn_crfsuite/__init__.py
index fe61bef..623fc0e 100644
--- a/sklearn_crfsuite/__init__.py
+++ b/sklearn_crfsuite/__init__.py
@@ -1,2 +1 @@
-# -*- coding: utf-8 -*-
 from .estimator import CRF
diff --git a/sklearn_crfsuite/_fileresource.py b/sklearn_crfsuite/_fileresource.py
index 3569cad..c28d63c 100644
--- a/sklearn_crfsuite/_fileresource.py
+++ b/sklearn_crfsuite/_fileresource.py
@@ -1,17 +1,16 @@
-# -*- coding: utf-8 -*-
-from __future__ import absolute_import
 import os
 import tempfile
 
 
-class FileResource(object):
+class FileResource:
     """
     Object that "owns" a file on a filesystem. If the ``filename`` is None,
     it maintains a temporary file which name is accessible via ``name``
     attribute; when pickling, the contents of this file is pickled;
     when unpickling, a new temp file is created; temp files are auto-deleted.
     """
-    def __init__(self, filename=None, keep_tempfiles=False, suffix='', prefix=''):
+
+    def __init__(self, filename=None, keep_tempfiles=False, suffix="", prefix=""):
         self.name = filename
         self.auto = filename is None
         self.keep_tempfiles = keep_tempfiles
@@ -19,7 +18,7 @@ def __init__(self, filename=None, keep_tempfiles=False, suffix='', prefix=''):
         self.prefix = prefix
 
     def ensure_name(self):
-        """ Ensure that a filename is available """
+        """Ensure that a filename is available"""
         if self.name is not None:
             return
         if self.auto:
@@ -28,7 +27,7 @@ def ensure_name(self):
             raise ValueError("File name is not provided")
 
     def cleanup(self):
-        """ Clean temporary files if needed """
+        """Clean temporary files if needed"""
         if self.keep_tempfiles or not self.auto:
             return
 
@@ -54,24 +53,23 @@ def __getstate__(self):
         dct = self.__dict__.copy()
 
         if self.auto:
-            filename = dct['name']
+            filename = dct["name"]
             if filename is not None:
                 try:
-                    with open(filename, 'rb') as f:
-                        dct['__FILE_RESOURCE_DATA__'] = f.read()
-                except IOError:
+                    with open(filename, "rb") as f:
+                        dct["__FILE_RESOURCE_DATA__"] = f.read()
+                except OSError:
                     pass
-                dct['name'] = None
+                dct["name"] = None
 
         return dct
 
     def __setstate__(self, state):
-        data = state.pop('__FILE_RESOURCE_DATA__', None)
+        data = state.pop("__FILE_RESOURCE_DATA__", None)
         self.__dict__.update(state)
 
         if data is not None:
             assert self.name is None
             self.ensure_name()
-            with open(self.name, 'wb') as f:
+            with open(self.name, "wb") as f:
                 f.write(data)
-
diff --git a/sklearn_crfsuite/compat.py b/sklearn_crfsuite/compat.py
index 34c2315..5360600 100644
--- a/sklearn_crfsuite/compat.py
+++ b/sklearn_crfsuite/compat.py
@@ -1,6 +1,6 @@
-# -*- coding: utf-8 -*-
 try:
     from sklearn.base import BaseEstimator
 except ImportError:
-    class BaseEstimator(object):
+
+    class BaseEstimator:
         pass
diff --git a/sklearn_crfsuite/estimator.py b/sklearn_crfsuite/estimator.py
index 298e20e..65f0891 100644
--- a/sklearn_crfsuite/estimator.py
+++ b/sklearn_crfsuite/estimator.py
@@ -1,13 +1,9 @@
-# -*- coding: utf-8 -*-
-from __future__ import absolute_import
-
-from six.moves import zip
-from tqdm import tqdm
 import pycrfsuite
+from tqdm import tqdm
 
 from sklearn_crfsuite._fileresource import FileResource
-from sklearn_crfsuite.trainer import LinePerIterationTrainer
 from sklearn_crfsuite.compat import BaseEstimator
+from sklearn_crfsuite.trainer import LinePerIterationTrainer
 
 
 class CRF(BaseEstimator):
@@ -207,37 +203,38 @@ class CRF(BaseEstimator):
         is to use pickle (or its alternatives like joblib).
 
     """
-    def __init__(self,
-                 algorithm=None,
-
-                 min_freq=None,
-                 all_possible_states=None,
-                 all_possible_transitions=None,
-                 c1=None,
-                 c2=None,
-                 max_iterations=None,
-                 num_memories=None,
-                 epsilon=None,
-                 period=None,
-                 delta=None,
-                 linesearch=None,
-                 max_linesearch=None,
-                 calibration_eta=None,
-                 calibration_rate=None,
-                 calibration_samples=None,
-                 calibration_candidates=None,
-                 calibration_max_trials=None,
-                 pa_type=None,
-                 c=None,
-                 error_sensitive=None,
-                 averaging=None,
-                 variance=None,
-                 gamma=None,
-
-                 verbose=False,
-                 model_filename=None,
-                 keep_tempfiles=False,
-                 trainer_cls=None):
+
+    def __init__(
+        self,
+        algorithm=None,
+        min_freq=None,
+        all_possible_states=None,
+        all_possible_transitions=None,
+        c1=None,
+        c2=None,
+        max_iterations=None,
+        num_memories=None,
+        epsilon=None,
+        period=None,
+        delta=None,
+        linesearch=None,
+        max_linesearch=None,
+        calibration_eta=None,
+        calibration_rate=None,
+        calibration_samples=None,
+        calibration_candidates=None,
+        calibration_max_trials=None,
+        pa_type=None,
+        c=None,
+        error_sensitive=None,
+        averaging=None,
+        variance=None,
+        gamma=None,
+        verbose=False,
+        model_filename=None,
+        keep_tempfiles=False,
+        trainer_cls=None,
+    ):
 
         self.algorithm = algorithm
         self.min_freq = min_freq
@@ -263,12 +260,14 @@ def __init__(self,
         self.averaging = averaging
         self.variance = variance
         self.gamma = gamma
+        self.model_filename = model_filename
+        self.keep_tempfiles = keep_tempfiles
 
         self.modelfile = FileResource(
             filename=model_filename,
             keep_tempfiles=keep_tempfiles,
             suffix=".crfsuite",
-            prefix="model"
+            prefix="model",
         )
         self.verbose = verbose
         self.trainer_cls = trainer_cls
@@ -295,7 +294,9 @@ def fit(self, X, y, X_dev=None, y_dev=None):
         y_dev : (optional) list of lists of strings
             Labels corresponding to X_dev.
         """
-        if (X_dev is None and y_dev is not None) or (X_dev is not None and y_dev is None):
+        if (X_dev is None and y_dev is not None) or (
+            X_dev is not None and y_dev is None
+        ):
             raise ValueError("Pass both X_dev and y_dev to use the holdout data")
 
         if self._tagger is not None:
@@ -308,7 +309,9 @@ def fit(self, X, y, X_dev=None, y_dev=None):
         train_data = zip(X, y)
 
         if self.verbose:
-            train_data = tqdm(train_data, "loading training data to CRFsuite", len(X), leave=True)
+            train_data = tqdm(
+                train_data, "loading training data to CRFsuite", len(X), leave=True
+            )
 
         for xseq, yseq in train_data:
             trainer.append(xseq, yseq)
@@ -320,7 +323,9 @@ def fit(self, X, y, X_dev=None, y_dev=None):
             test_data = zip(X_dev, y_dev)
 
             if self.verbose:
-                test_data = tqdm(test_data, "loading dev data to CRFsuite", len(X_dev), leave=True)
+                test_data = tqdm(
+                    test_data, "loading dev data to CRFsuite", len(X_dev), leave=True
+                )
 
             for xseq, yseq in test_data:
                 trainer.append(xseq, yseq, 1)
@@ -412,6 +417,7 @@ def score(self, X, y):
         For other metrics check :mod:`sklearn_crfsuite.metrics`.
         """
         from sklearn_crfsuite.metrics import flat_accuracy_score
+
         y_pred = self.predict(X)
         return flat_accuracy_score(y, y_pred)
 
@@ -446,7 +452,7 @@ def size_(self):
         """
         if self._info is None:
             return None
-        return int(self._info.header['size'])
+        return int(self._info.header["size"])
 
     @property
     def num_attributes_(self):
@@ -455,7 +461,7 @@ def num_attributes_(self):
         """
         if self._info is None:
             return None
-        return int(self._info.header['num_attrs'])
+        return int(self._info.header["num_attrs"])
 
     @property
     def attributes_(self):
@@ -502,29 +508,29 @@ def _info(self):
     def _get_trainer(self):
         trainer_cls = self.trainer_cls or LinePerIterationTrainer
         params = {
-            'feature.minfreq': self.min_freq,
-            'feature.possible_states': self.all_possible_states,
-            'feature.possible_transitions': self.all_possible_transitions,
-            'c1': self.c1,
-            'c2': self.c2,
-            'max_iterations': self.max_iterations,
-            'num_memories': self.num_memories,
-            'epsilon': self.epsilon,
-            'period': self.period,
-            'delta': self.delta,
-            'linesearch': self.linesearch,
-            'max_linesearch': self.max_linesearch,
-            'calibration.eta': self.calibration_eta,
-            'calibration.rate': self.calibration_rate,
-            'calibration.samples': self.calibration_samples,
-            'calibration.candidates': self.calibration_candidates,
-            'calibration.max_trials': self.calibration_max_trials,
-            'type': self.pa_type,
-            'c': self.c,
-            'error_sensitive': self.error_sensitive,
-            'averaging': self.averaging,
-            'variance': self.variance,
-            'gamma': self.gamma,
+            "feature.minfreq": self.min_freq,
+            "feature.possible_states": self.all_possible_states,
+            "feature.possible_transitions": self.all_possible_transitions,
+            "c1": self.c1,
+            "c2": self.c2,
+            "max_iterations": self.max_iterations,
+            "num_memories": self.num_memories,
+            "epsilon": self.epsilon,
+            "period": self.period,
+            "delta": self.delta,
+            "linesearch": self.linesearch,
+            "max_linesearch": self.max_linesearch,
+            "calibration.eta": self.calibration_eta,
+            "calibration.rate": self.calibration_rate,
+            "calibration.samples": self.calibration_samples,
+            "calibration.candidates": self.calibration_candidates,
+            "calibration.max_trials": self.calibration_max_trials,
+            "type": self.pa_type,
+            "c": self.c,
+            "error_sensitive": self.error_sensitive,
+            "averaging": self.averaging,
+            "variance": self.variance,
+            "gamma": self.gamma,
         }
         params = {k: v for k, v in params.items() if v is not None}
         return trainer_cls(
@@ -535,6 +541,6 @@ def _get_trainer(self):
 
     def __getstate__(self):
         dct = self.__dict__.copy()
-        dct['_tagger'] = None
-        dct['_info_cached'] = None
+        dct["_tagger"] = None
+        dct["_info_cached"] = None
         return dct
diff --git a/sklearn_crfsuite/metrics.py b/sklearn_crfsuite/metrics.py
index fe7d026..6f1d0b1 100644
--- a/sklearn_crfsuite/metrics.py
+++ b/sklearn_crfsuite/metrics.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-from __future__ import absolute_import, division
 from functools import wraps
 
 from sklearn_crfsuite.utils import flatten
@@ -11,6 +9,7 @@ def wrapper(y_true, y_pred, *args, **kwargs):
         y_true_flat = flatten(y_true)
         y_pred_flat = flatten(y_pred)
         return func(y_true_flat, y_pred_flat, *args, **kwargs)
+
     return wrapper
 
 
@@ -20,6 +19,7 @@ def flat_accuracy_score(y_true, y_pred):
     Return accuracy score for sequence items.
     """
     from sklearn import metrics
+
     return metrics.accuracy_score(y_true, y_pred)
 
 
@@ -29,6 +29,7 @@ def flat_precision_score(y_true, y_pred, **kwargs):
     Return precision score for sequence items.
     """
     from sklearn import metrics
+
     return metrics.precision_score(y_true, y_pred, **kwargs)
 
 
@@ -38,6 +39,7 @@ def flat_recall_score(y_true, y_pred, **kwargs):
     Return recall score for sequence items.
     """
     from sklearn import metrics
+
     return metrics.recall_score(y_true, y_pred, **kwargs)
 
 
@@ -47,6 +49,7 @@ def flat_f1_score(y_true, y_pred, **kwargs):
     Return F1 score for sequence items.
     """
     from sklearn import metrics
+
     return metrics.f1_score(y_true, y_pred, **kwargs)
 
 
@@ -56,7 +59,8 @@ def flat_fbeta_score(y_true, y_pred, beta, **kwargs):
     Return F-beta score for sequence items.
     """
     from sklearn import metrics
-    return metrics.fbeta_score(y_true, y_pred, beta, **kwargs)
+
+    return metrics.fbeta_score(y_true, y_pred, beta=beta, **kwargs)
 
 
 @_flattens_y
@@ -65,6 +69,7 @@ def flat_classification_report(y_true, y_pred, labels=None, **kwargs):
     Return classification report for sequence items.
     """
     from sklearn import metrics
+
     return metrics.classification_report(y_true, y_pred, labels, **kwargs)
 
 
@@ -77,7 +82,8 @@ def sequence_accuracy_score(y_true, y_pred):
     if not total:
         return 0
 
-    matches = sum(1 for yseq_true, yseq_pred in zip(y_true, y_pred)
-                  if yseq_true == yseq_pred)
+    matches = sum(
+        1 for yseq_true, yseq_pred in zip(y_true, y_pred) if yseq_true == yseq_pred
+    )
 
     return matches / total
diff --git a/sklearn_crfsuite/scorers.py b/sklearn_crfsuite/scorers.py
index 0e51a43..24a19f9 100644
--- a/sklearn_crfsuite/scorers.py
+++ b/sklearn_crfsuite/scorers.py
@@ -1,12 +1,11 @@
-# -*- coding: utf-8 -*-
 """
 Scorer functions to use with scikit-learn ``cross_val_score``,
 ``GridSearchCV``, ``RandomizedSearchCV`` and other similar classes.
 """
+
 from sklearn.metrics import make_scorer
 
 from sklearn_crfsuite import metrics
 
-
 flat_accuracy = make_scorer(metrics.flat_accuracy_score)
 sequence_accuracy = make_scorer(metrics.sequence_accuracy_score)
diff --git a/sklearn_crfsuite/trainer.py b/sklearn_crfsuite/trainer.py
index 3aa2cd3..3457584 100644
--- a/sklearn_crfsuite/trainer.py
+++ b/sklearn_crfsuite/trainer.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 import pycrfsuite
 from tabulate import tabulate
 
@@ -8,6 +7,7 @@ class LinePerIterationTrainer(pycrfsuite.Trainer):
     This pycrfsuite.Trainer prints information about each iteration
     on a single line.
     """
+
     def on_iteration(self, log, info):
         parts = [
             "Iter {num:<3} ",
@@ -15,18 +15,18 @@ def on_iteration(self, log, info):
             "loss={loss:<8.2f} ",
         ]
 
-        if 'active_features' in info:
+        if "active_features" in info:
             parts += ["active={active_features:<5} "]
 
-        if 'avg_precision' in info:
+        if "avg_precision" in info:
             parts += [
                 "precision={avg_precision:0.3f}  ",
                 "recall={avg_recall:0.3f}  ",
                 "F1={avg_f1:0.3f}  ",
-                "Acc(item/seq)={item_accuracy_float:0.3f} {instance_accuracy_float:0.3f}  "
+                "Acc(item/seq)={item_accuracy_float:0.3f} {instance_accuracy_float:0.3f}  ",
             ]
 
-        if 'feature_norm' in info:
+        if "feature_norm" in info:
             parts += ["feature_norm={feature_norm:<8.2f}"]
 
         line = "".join(parts)
@@ -34,17 +34,18 @@ def on_iteration(self, log, info):
 
     def on_optimization_end(self, log):
         last_iter = self.logparser.last_iteration
-        if last_iter.get('scores', None):
+        if last_iter.get("scores", None):
             data = [
                 [entity, score.precision, score.recall, score.f1 or 0, score.ref]
-                for entity, score in sorted(last_iter['scores'].items())
+                for entity, score in sorted(last_iter["scores"].items())
             ]
-            table = tabulate(data,
+            table = tabulate(
+                data,
                 headers=["Label", "Precision", "Recall", "F1", "Support"],
                 floatfmt="0.3f",
             )
             size = len(table.splitlines()[0])
-            print("="*size)
+            print("=" * size)
             print(table)
-            print("-"*size)
-        super(LinePerIterationTrainer, self).on_optimization_end(log)
+            print("-" * size)
+        super().on_optimization_end(log)
diff --git a/sklearn_crfsuite/utils.py b/sklearn_crfsuite/utils.py
index 7999ba8..788453b 100644
--- a/sklearn_crfsuite/utils.py
+++ b/sklearn_crfsuite/utils.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 from itertools import chain
 
 
diff --git a/tests/conftest.py b/tests/conftest.py
index 93f710a..96810f1 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,24 +1,33 @@
-# -*- coding: utf-8 -*-
-from __future__ import absolute_import
 import pytest
 
 
 @pytest.fixture()
 def xseq():
     return [
-        {'walk': 1, 'shop': 0.5},
-        {'walk': 1},
-        {'walk': 1, 'clean': 0.5},
-        {u'shop': 0.5, u'clean': 0.5},
-        {'walk': 0.5, 'clean': 1},
-        {'clean': 1, u'shop': 0.1},
-        {'walk': 1, 'shop': 0.5},
+        {"walk": 1, "shop": 0.5},
+        {"walk": 1},
+        {"walk": 1, "clean": 0.5},
+        {"shop": 0.5, "clean": 0.5},
+        {"walk": 0.5, "clean": 1},
+        {"clean": 1, "shop": 0.1},
+        {"walk": 1, "shop": 0.5},
         {},
-        {'clean': 1},
-        {u'солнце': u'не светит'.encode('utf8'), 'clean': 1},
+        {"clean": 1},
+        {"солнце": "не светит".encode(), "clean": 1},
     ]
 
+
 @pytest.fixture
 def yseq():
-    return ['sunny', 'sunny', u'sunny', 'rainy', 'rainy', 'rainy',
-            'sunny', 'sunny', 'rainy', 'rainy']
+    return [
+        "sunny",
+        "sunny",
+        "sunny",
+        "rainy",
+        "rainy",
+        "rainy",
+        "sunny",
+        "sunny",
+        "rainy",
+        "rainy",
+    ]
diff --git a/tests/test_crf.py b/tests/test_crf.py
index 13ed675..303324b 100644
--- a/tests/test_crf.py
+++ b/tests/test_crf.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 import os
 import pickle
 
@@ -7,8 +6,7 @@
 
 from sklearn_crfsuite import CRF
 
-
-ALGORITHMS =  ["lbfgs", "l2sgd", "pa", "ap", "arow"]
+ALGORITHMS = ["lbfgs", "l2sgd", "pa", "ap", "arow"]
 
 
 @pytest.mark.parametrize("algorithm", ALGORITHMS)
@@ -17,7 +15,7 @@ def test_crf(xseq, yseq, algorithm):
     crf.fit([xseq], [yseq])
 
     y_pred = crf.predict([xseq])
-    if algorithm != 'ap':  # Averaged Perceptron is regularized too much
+    if algorithm != "ap":  # Averaged Perceptron is regularized too much
         assert y_pred == [yseq]
 
 
@@ -31,14 +29,9 @@ def test_crf_verbose(xseq, yseq, algorithm, use_dev):
     else:
         X_dev, y_dev = None, None
 
-    crf.fit(
-        X=[xseq, xseq],
-        y=[yseq, yseq],
-        X_dev=X_dev,
-        y_dev=y_dev
-    )
+    crf.fit(X=[xseq, xseq], y=[yseq, yseq], X_dev=X_dev, y_dev=y_dev)
     y_pred = crf.predict([xseq])
-    if algorithm != 'ap':  # Averaged Perceptron is regularized too much
+    if algorithm != "ap":  # Averaged Perceptron is regularized too much
         assert y_pred == [yseq]
 
 
@@ -72,7 +65,7 @@ def test_crf_score(xseq, yseq, algorithm):
     crf.fit([xseq], [yseq])
 
     score = crf.score([xseq], [yseq])
-    if algorithm != 'ap':
+    if algorithm != "ap":
         assert score == 1.0
     else:  # Averaged Perceptron is regularized too much
         assert score > 0.8
@@ -86,7 +79,7 @@ def test_crf_pickling(xseq, yseq, algorithm):
 
     crf2 = pickle.loads(data)
     score = crf2.score([xseq], [yseq])
-    if algorithm != 'ap':
+    if algorithm != "ap":
         assert score == 1.0
     else:  # Averaged Perceptron is regularized too much
         assert score > 0.8
@@ -138,16 +131,16 @@ def test_attributes(xseq, yseq):
     assert crf.state_features_ is None
     assert crf.transition_features_ is None
 
-    crf.fit([xseq]*20, [yseq]*20)
+    crf.fit([xseq] * 20, [yseq] * 20)
 
     assert crf.tagger_ is not None
     assert crf.size_ > 1000
-    assert set(crf.classes_) == {'sunny', 'rainy'}
+    assert set(crf.classes_) == {"sunny", "rainy"}
 
     assert crf.num_attributes_ > 0
     assert len(crf.attributes_) == crf.num_attributes_
     assert all(crf.attributes_)
-    assert 'clean' in crf.attributes_
+    assert "clean" in crf.attributes_
 
     assert len(crf.state_features_) > 0
     assert all(isinstance(c, float) for c in crf.state_features_.values())
diff --git a/tests/test_metrics.py b/tests/test_metrics.py
index c5a505e..f98e514 100644
--- a/tests/test_metrics.py
+++ b/tests/test_metrics.py
@@ -1,11 +1,7 @@
-# -*- coding: utf-8 -*-
-from __future__ import absolute_import, division
-
 import pytest
 
 from sklearn_crfsuite import metrics
 
-
 y1 = [["x", "z", "y"], ["x", "x"]]
 y2 = [["y", "z", "y"], ["x", "y"]]
 
@@ -16,30 +12,34 @@ def test_flat_accuracy():
 
 
 def test_flat_precision():
-    score = metrics.flat_precision_score(y1, y2, average='micro')
+    score = metrics.flat_precision_score(y1, y2, average="micro")
     assert score == 3 / 5
 
 
 def test_flat_recall():
-    score = metrics.flat_recall_score(y1, y2, average='micro')
+    score = metrics.flat_recall_score(y1, y2, average="micro")
     assert score == 3 / 5
 
 
 def test_flat_fscore():
-    score = metrics.flat_f1_score(y1, y2, average='macro')
+    score = metrics.flat_f1_score(y1, y2, average="macro")
     assert score == 2 / 3
-    assert metrics.flat_fbeta_score(y1, y2, beta=1, average='macro') == score
+    assert metrics.flat_fbeta_score(y1, y2, beta=1, average="macro") == score
 
 
-@pytest.mark.xfail(reason="see https://github.com/TeamHG-Memex/sklearn-crfsuite/issues/1")
+@pytest.mark.xfail(
+    reason="see https://github.com/TeamHG-Memex/sklearn-crfsuite/issues/1"
+)
 def test_flat_f1_score_binary():
     s = [["x", "y"], ["x", "y"]]
-    score = metrics.flat_f1_score(s, s, average='weighted')
+    score = metrics.flat_f1_score(s, s, average="weighted")
     assert score == 1.0
 
 
 def test_sequence_accuracy():
     assert metrics.sequence_accuracy_score(y1, y2) == 0
     assert metrics.sequence_accuracy_score([], []) == 0
-    assert metrics.sequence_accuracy_score([[1,2], [3], [4]], [[1,2], [4], [4]]) == 2 / 3
-    assert metrics.sequence_accuracy_score([[1,2], [3]], [[1,2], [3]]) == 1.0
+    assert (
+        metrics.sequence_accuracy_score([[1, 2], [3], [4]], [[1, 2], [4], [4]]) == 2 / 3
+    )
+    assert metrics.sequence_accuracy_score([[1, 2], [3]], [[1, 2], [3]]) == 1.0
diff --git a/tox.ini b/tox.ini
index b204ad6..fdb8599 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,15 +1,40 @@
 [tox]
-envlist = py27,py34,py35,py36
+envlist = pre-commit,docs,twinecheck,min,py38,py39,py310,py311,py312
 
 [testenv]
 deps=
     pytest
     pytest-cov
-    numpy
-
 commands=
-    pip install -U wheel pip
-    pip install scipy
-    pip install scikit-learn
-    pip install -e .
-    py.test --doctest-modules --cov=sklearn_crfsuite --cov-report= {posargs: sklearn_crfsuite tests}
+    pytest --doctest-modules --cov=sklearn_crfsuite --cov-report= {posargs:sklearn_crfsuite tests}
+
+[testenv:min]
+basepython = python3.8
+deps =
+    {[testenv]deps}
+    python-crfsuite==0.9.7
+    scikit-learn==0.24.0
+    tabulate==0.4.2
+    tqdm==2.0
+
+[testenv:pre-commit]
+deps =
+    pre-commit
+commands = pre-commit run --all-files --show-diff-on-failure
+
+[testenv:docs]
+basepython = python3
+changedir = docs
+deps =
+    -rdocs/requirements.txt
+commands =
+    sphinx-build -W -b html . {envtmpdir}/html
+
+[testenv:twinecheck]
+basepython = python3
+deps =
+    twine==5.0.0
+    build==1.1.1
+commands =
+    python -m build --sdist
+    twine check dist/*