def Perm.value
import bend-collections-laws-crypto@1.0.0.0/spec/math/natural.bend as Naturalimport Base
import bend-collections-laws-crypto@1.0.0.0/src/math/natural.bend as M
185def Perm.value(+n: Nat, +k: Nat) -> Type:
186 {M.perm(n, k) == desc(n, k) : Nat}