def get_unit_hostnames(self, units):
        """Return a dict of juju unit names to hostnames."""
        host_names = {}
        for unit in units:
            host_names[unit.info['unit_name']] = \
                str(unit.file_contents('/etc/hostname').strip())
        self.log.debug('Unit host names: {}'.format(host_names))
        return host_names
Return a dict of juju unit names to hostnames.