fact: Definition fully_faithful_1cell_weq_fully_faithful {B : bicat} {a b : B} (f : a --> b) : (fully_faithful_1cell f) ≃ (∏ (z : B), fully_faithful (post_comp z f)).
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.Core.Isos UniMath.Bicategories.Core.Bicat UniMath.Bicategories.Core.Invertible_2cells