Here is an example involving the unicode character MIDDLE DOT · : The line

ab·cd = 7

is valid Python 3 code and is happily accepted by the CPython interpreter. However, tokenize.py does not like it. It says that the middle-dot is an error token. Here is an example you can run to see that:

    import tokenize
    from io import BytesIO
    
    test = 'ab·cd = 7'.encode('utf-8')
    
    x = tokenize.tokenize(BytesIO(test).readline)
    for i in x: print(i)

For reference, the official definition of identifiers is: 

https://docs.python.org/3.6/reference/lexical_analysis.html#identifiers

and details about MIDDLE DOT are at

https://www.unicode.org/Public/10.0.0/ucd/PropList.txt

MIDDLE DOT has the "Other_ID_Continue" property, so I think the interpreter is behaving correctly (i.e. consistent with the documented spec), while tokenize.py is wrong.