module FunMenv : MENV = struct

  type 'a menv = (string -> 'a option)

  let empty = fun s -> raise (Failure "unimplemented") (* replace this stub *)

  let bind name valu env = raise (Failure "unimplemented") (* replace this stub *)

  let make names values = raise (Failure "unimplemented") (* replace this stub *)

  let lookup name env = raise (Failure "unimplemented") (* replace this stub *)

  let merge env1 env2 = raise (Failure "unimplemented") (* replace this stub *)

end