def compose(fun1, fun2):
    # Fill in
    """
    Returns a new function f. f should take a single input i, and return
    fun1(fun2(i))
    :param fun1: function
    :param fun2: function
    :return: function
    """
    def retfun(i):
        # Fill in
        return fun1(fun2(i))
        pass
    return retfun