Although this is just the version published to pypi. I don't know what
version sip is using. The version published on pypi is apparently stable
and mature and any further changes on github are simplifications that
the author doesn't particularly want to support.
I don't know if we actually hit the parsing code in our workflows but it
is published as a dependancy.
The latest version talks about removing optional stuff from the API a
bunch. But sip just uses `from ply import lex, yacc` so hopefully that
is a stable part of the API. Even if sip is using the newer one.
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