- added `--check`
- only put trailing commas in function signatures and calls if it's safe to do so. If
the file is Python 3.6+ it's always safe, otherwise only safe if there are no `*args`
or `**kwargs` used in the signature or call. (8)
- fixed invalid spacing of dots in relative imports (6, 13)
- fixed invalid splitting after comma on unpacked variables in for-loops (23)
- fixed spurious space in parenthesized set expressions (7)
- fixed spurious space after opening parentheses and in default arguments (14, 17)
- fixed spurious space after unary operators when the operand was a complex expression
(15)