fact: Definition concatenate' {X:UU} {m n:nat} (f : ⟦m⟧ -> X) (g : ⟦n⟧ -> X) : ⟦m+n⟧ -> X.
imports: UniMath.Foundations.NaturalNumbers UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.DecidablePropositions UniMath.MoreFoundations.NegativePropositions