Corrected/improved the English + comments

[mark-summerfield]

Personally, I'd change the my_repr variable's name to output or data throughout.

Also, in many places I'd have replaced "specific" with "custom".

You could consider adopting the new typing module's syntax, e.g., _type_name = typing.List[int, int, int], etc.

The - signs on lines 339, 340, 342, and 343 look wrong to me. Personally I never leave whitespace after a unary operator.

[severin-lemaignan]

Closed by c0b5854c5791491d5 Other comment tracked in #744