fact: Definition isassoc_concatenate {X : UU} (x y z : Sequence X) : concatenate (concatenate x y) z = concatenate x (concatenate y z).
imports: UniMath.Combinatorics.FiniteSets UniMath.Combinatorics.Lists UniMath.Combinatorics.Vectors UniMath.MoreFoundations.PartA UniMath.MoreFoundations.Tactics