DONT USE. Will be deleted soon. Use ``self.of``!

def of_cls(self):
        """
        DONT USE. Will be deleted soon. Use ``self.of``!
        """
        if isinstance(self.of, six.string_types):
            warnings.warn('When using Range programatically, dont pass "of" param as string!')
            return Register.get_task_cls(self.of)
        return self.of