diff --git a/README.md b/README.md
index c0f3e9eef..11e0fd9ce 100644
--- a/README.md
+++ b/README.md
@@ -1,32 +1,6 @@
 # Downloads
 [![Downloads](https://pepy.tech/badge/pony)](https://pepy.tech/project/pony) [![Downloads](https://pepy.tech/badge/pony/month)](https://pepy.tech/project/pony/month) [![Downloads](https://pepy.tech/badge/pony/week)](https://pepy.tech/project/pony/week)
 
-# Tests
-
-#### PostgreSQL
-Python 2 <a href="http://jenkins.agilecode.io:8111/viewType.html?buildTypeId=GithubPonyORMCi_Python2postgres&guest=1">
-<img src="http://jenkins.agilecode.io:8111/app/rest/builds/buildType:(id:GithubPonyORMCi_Python2postgres)/statusIcon"/>
-</a>
-Python 3 <a href="http://jenkins.agilecode.io:8111/viewType.html?buildTypeId=GithubPonyORMCi_Python3postgres&guest=1">
-<img src="http://jenkins.agilecode.io:8111/app/rest/builds/buildType:(id:GithubPonyORMCi_Python3postgres)/statusIcon"/>
-</a>
-
-#### SQLite
-Python 2 <a href="http://jenkins.agilecode.io:8111/viewType.html?buildTypeId=GithubPonyORMCi_Python2sqlite&guest=1">
-<img src="http://jenkins.agilecode.io:8111/app/rest/builds/buildType:(id:GithubPonyORMCi_Python2sqlite)/statusIcon"/>
-</a>
-Python 3 <a href="http://jenkins.agilecode.io:8111/viewType.html?buildTypeId=GithubPonyORMCi_Python3sqlite&guest=1">
-<img src="http://jenkins.agilecode.io:8111/app/rest/builds/buildType:(id:GithubPonyORMCi_Python3sqlite)/statusIcon"/>
-</a>
-
-#### CockroachDB
-Python 2 <a href="http://jenkins.agilecode.io:8111/viewType.html?buildTypeId=GithubPonyORMCi_Python2cockroach&guest=1">
-<img src="http://jenkins.agilecode.io:8111/app/rest/builds/buildType:(id:GithubPonyORMCi_Python2cockroach)/statusIcon"/>
-</a>
-Python 3 <a href="http://jenkins.agilecode.io:8111/viewType.html?buildTypeId=GithubPonyORMCi_Python3cockroach&guest=1">
-<img src="http://jenkins.agilecode.io:8111/app/rest/builds/buildType:(id:GithubPonyORMCi_Python3cockroach)/statusIcon"/>
-</a>
-
 
 Pony Object-Relational Mapper
 =============================
diff --git a/pony/thirdparty/compiler/ast.py b/pony/thirdparty/compiler/ast.py
index e5596d4b6..9a17fea4b 100644
--- a/pony/thirdparty/compiler/ast.py
+++ b/pony/thirdparty/compiler/ast.py
@@ -8,14 +8,15 @@
 from .consts import CO_VARARGS, CO_VARKEYWORDS
 
 def flatten(seq):
+    def helper(push, _seq):
+        for el in _seq:
+            if type(el) in (tuple, list):
+                helper(push, el)
+            else:
+                push(el)
+
     l = []
-    for elt in seq:
-        t = type(elt)
-        if t is tuple or t is list:
-            for elt2 in flatten(elt):
-                l.append(elt2)
-        else:
-            l.append(elt)
+    helper(l.append, seq)
     return l
 
 def flatten_nodes(seq):