* Blacken .py files in blib2to3
This is in preparation for adding type annotations to blib2to3 in
order to compiling it with mypyc (#1009, which I can rebase on top of
this).
To enforce that it stays blackened, I just cargo-culted the existing
test code used for validating formatting. It feels pretty clunky now,
though, so I can abstract the common logic out into a helper if that
seems better. (But error messages might be less clear then?)
* Tidy up the tests
* Parse `:=` properly
* never unwrap parenthesis around `:=`
* When checking for AST-equivalence, use `ast` instead of `typed-ast` when running on python >=3.8
* Assume code that uses `:=` is at least 3.8
Since black.py is not marked as executable, the shebang in black.py serves
no purpose. black should be invoked through its entry point any way.
token.py is an internal module without a __name__ == '__main__' block or
other executable code. It contains just list of constants and small
helper functions.
Signed-off-by: Christian Heimes <christian@python.org>
