def converge(self, playbook=None, **kwargs):
        """
        Executes ``ansible-playbook`` against the converge playbook unless
        specified otherwise and returns a string.

        :param playbook: An optional string containing an absolute path to a
         playbook.
        :param kwargs: An optional keyword arguments.
        :return: str
        """
        if playbook is None:
            pb = self._get_ansible_playbook(self.playbooks.converge, **kwargs)
        else:
            pb = self._get_ansible_playbook(playbook, **kwargs)

        return pb.execute()