fact: Definition has_comma (B : bicat) : UU := ∏ (b₁ b₂ b₃ : B) (f : b₁ --> b₃) (g : b₂ --> b₃), ∑ (p : comma_cone f g), has_comma_ump p.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.Bicategories.Core.Bicat UniMath.Bicategories.Core.Invertible_2cells UniMath.Bicategories.Core.Univalence