'Set or unset forced_down flag for the service'

def _forced_down(self, body, context):

    try:
        forced_down = strutils.bool_from_string(body['forced_down'])
    except KeyError:
        msg = _('Missing    forced_down    field')
        raise webob.exc.HTTPBadRequest(explanation=msg)
    host = body['host']
    binary = body['binary']
    ret_value = {'service': {'host': host, 'binary': binary, 'forced_down': forced_down}}
    self._update(context, host, binary, {'forced_down': forced_down})
    return ret_value
