[py] keywords being illegally assigned as variables get highlighted as variables

[mtaran-google]

keywords (e.g. and, as in, from, with) should be highlighted as keywords even when they are incorrectly being assigned to, since that actually errors out and doesn't work.

e.g.

  in = 1

should have the in be keyword-colored

[marijnh]

This is a property of the parsing approach used here—it'll only match a token when that token is actually valid in that context. This is sometimes a boon, as in Kotlin and JavaScript's contextual keywords, and sometimes produces somewhat unexpected highlighting, as in this case.

My view is that since the modes aren't error-checkers, odd highlighting on invalid inputs is acceptable. Is that something you can live with?