fact: Definition subst_var {L : lambda_calculus_data} {m n} i (f : stn m → L n) : subst (var i) f = f i := pr122 (pr222 L) m n i f.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Combinatorics.StandardFiniteSets UniMath.Combinatorics.Tuples