code: def mpim_open(self, *, users: List[str], **kwargs) -> SlackResponse:
          
          kwargs.update({"users": users})
          return self.api_call("mpim.open", json=kwargs)
docs: 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']