A subset of lib2to3 taken from Python 3.7.0b2. Commit hash: 9c17e3a1987004b8bcfbe423953aad84493a7984 Reasons for forking: - consistent handling of f-strings for users of Python < 3.6.2 - backport of BPO-33064 that fixes parsing files with trailing commas after *args and **kwargs - backport of GH-6143 that restores the ability to reformat legacy usage of `async` - better ability to debug (better reprs for starters) - ability to Cythonize