Wrapper for Python's stdlib `tokenize` supporting roundtrips
Description
The stdlib tokenize module does not properly roundtrip. This wrapper
around the stdlib provides two additional tokens ESCAPED_NL and
UNIMPORTANT_WS, and a Token data type. Use src_to_tokens and
tokens_to_src to roundtrip. This library is useful if you are writing
a refactoring tool based on the python tokenization.
