Lean4
/-- Copy of a `BiheytingHom` with a new `toFun` equal to the old one. Useful to fix definitional
equalities. -/
protected def copy (f : BiheytingHom α β) (f' : α → β) (h : f' = f) : BiheytingHom α β
where
toFun := f'
map_sup' := by simpa only [h] using map_sup f
map_inf' := by simpa only [h] using map_inf f
map_himp' := by simpa only [h] using map_himp f
map_sdiff' := by simpa only [h] using map_sdiff f