Consider the following Haskell datatype definitions for representing simple lambda calculus terms. data Term = Var String | Application Term Term | Lambda String Term

Define the following utility functions

a) normalForm :: Term -> Bool, checks if a term is in normal form, meaning it contains no application (no matter how deeply embedded) whose left hand side is a lambda expression

. b) listOVars :: [String], an infinite list of distinct variables that can be used if you want to find a fresh variable.