type inner_storage is michelson_or (int, "one", nat, "two")

type storage is
  michelson_or (int, "three", inner_storage, "")

type return is list (operation) * storage

function main (const action : unit; const store : storage)
  : return is
block {
  const foo : storage
  = (M_right ((M_left (1) : inner_storage)) : storage)
} with ((nil : list (operation)), (foo : storage))