Add an 'iterate' function to Utils

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

Utils.agda

@@ -1,5 +1,6 @@
 module Utils where
 
+open import Data.Nat using (ℕ; suc)
 open import Data.List using (List; []; _∷_; _++_)
 open import Data.List.Membership.Propositional using (_∈_)
 open import Data.List.Relation.Unary.All using (All; []; _∷_; map)
@@ -34,3 +35,7 @@ All¬-¬Any {l = x ∷ xs} (_ ∷ ¬Pxs) (there Pxs) = All¬-¬Any ¬Pxs Pxs
 All-x∈xs : ∀ {a} {A : Set a} (xs : List A) → All (λ x → x ∈ xs) xs
 All-x∈xs [] = []
 All-x∈xs (x ∷ xs') = here refl ∷ map there (All-x∈xs xs')
+
+iterate : ∀ {a} {A : Set a} (n : ℕ) → (f : A → A) → A → A
+iterate 0 _ a = a
+iterate (suc n) f a = f (iterate n f a)