mathlib

fbb49cbe - refactor(*): place map_map in the functor namespace (#3309)

refactor(*): place map_map in the functor namespace (#3309) Renames `_root_.map_map` to `functor.map_map` and `filter.comap_comap_comp` to `filter.comap_comap` (which is consistent with `filter.map_map`).