kahlan\Allow::toBe PHP Method

    public function toBe()
    {
        if (!is_string($this->_actual)) {
            throw new Exception("Error `toBe()` need to be applied on a fully-namespaced class or function name.");
        }
        $method = Monkey::patch($this->_actual);
        call_user_func_array([$method, 'toBe'], func_get_args());
    }