fact: Definition make_unit_diagram {C : category} (point : C) : diagram unit_graph C.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Limits.Graphs.Colimits UniMath.Combinatorics.StandardFiniteSets UniMath.Combinatorics.FiniteSets