This method opens a multiparty direct message.

        Args:
            users (list): A lists of user ids. The ordering of the users
                is preserved whenever a MPIM group is returned.
                e.g. ['W1234567890', 'U2345678901', 'U3456789012']

def mpim_open(self, *, users: List[str], **kwargs) -> SlackResponse:
        """This method opens a multiparty direct message.

        Args:
            users (list): A lists of user ids. The ordering of the users
                is preserved whenever a MPIM group is returned.
                e.g. ['W1234567890', 'U2345678901', 'U3456789012']
        """
        kwargs.update({"users": users})
        return self.api_call("mpim.open", json=kwargs)