Get a string summarising the state of Rez as a whole.

        Returns:
            String.

def get_summary_string(self):
        """Get a string summarising the state of Rez as a whole.

        Returns:
            String.
        """
        from rez.plugin_managers import plugin_manager

        txt = "Rez %s" % __version__
        txt += "\n\n%s" % plugin_manager.get_summary_string()
        return txt