This function takes a single string as an argument.
Hello, my cat. And my cat doesn't say "hello" back.
It returns a dictionary of words and their counts:
{'hello': 2, 'my': 2, 'cat': 2, 'and': 1, "doesn't": 1, 'say': 1, 'back': 1}
Case should be ignored. Output keys must be lowercase.
Key order in the dictionary doesn't matter.
Split the strings into words on any whitespace.
Ignore each of the following characters:
" : ; , . - + = / \ | [ ] { } ( ) * ^ &
If the input is empty or contains only ignored characters, return an empty dictionary.