'Set external id.'

def set_external_id(self, key, value):

    if self.exists():
        cmd = ['br-set-external-id', self.bridge, key]
        if value:
            cmd += [value]
        (rtc, _, err) = self._vsctl(cmd)
        if (rtc != 0):
            self.module.fail_json(msg=err)
        return True
    return False
