fact: Definition const_matrix {X : UU} {n m : nat} (x : X) : Matrix X n m := const_vec (const_vec x).
imports: UniMath.Combinatorics.FiniteSets UniMath.Combinatorics.Lists UniMath.Combinatorics.Vectors UniMath.MoreFoundations.PartA UniMath.MoreFoundations.Tactics