fact: Definition equiv_precompose `{Funext} {A B C : Type} (f : A -> B) `{IsEquiv A B f} : (B -> C) <~> (A -> C) := Build_Equiv _ _ (fun (g:B->C) => g o f) _.
imports: Basics.Overture Basics.PathGroupoids Basics.Contractible Basics.Tactics