fact: Definition stnprod_step { n : nat } ( f : ⟦S n⟧ -> nat ) : stnprod f = stnprod (f ∘ dni lastelement) * f lastelement.
imports: UniMath.Foundations.NaturalNumbers UniMath.MoreFoundations.Tactics UniMath.MoreFoundations.DecidablePropositions UniMath.MoreFoundations.NegativePropositions