fact: Definition weqfromcoprodofstn_invmap (n m : nat) : ⟦n + m⟧ -> (⟦n⟧ ⨿ ⟦m⟧).
imports: UniMath.Foundations.NaturalNumbers UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.DecidablePropositions UniMath.MoreFoundations.NegativePropositions