fact: Definition subst_subst {L : lambda_calculus_data} {l m n} t (g : stn l → L m) (f : stn m → L n) : subst (subst t g) f = subst t (λ i, subst (g i) f) := pr122 (pr222 (pr222 L)) l m n t g f.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Combinatorics.StandardFiniteSets UniMath.Combinatorics.Tuples