docs: def usage(asked_for=0):
      '''Exit with a usage string, used for bad argument or with -h'''
      exit =  fsq.const('FSQ_SUCCESS') if asked_for else\
                  fsq.const('FSQ_FAIL_PERM')
      f = sys.stdout if asked_for else sys.stderr
      shout('{0} [opts] src_queue trg_queue host item_id [item_id [...]]'.format(
            os.path.basename(_PROG)), f)
      if asked_for:
          shout('{0} [-p|--protocol=jsonrpc] [-L|--no-lock] [-t|--trigger] '\
                '[-i|--ignore-listener] <proto>://<host>:<port>/url'\
                .format(os.path.basename(_PROG)), f)
          shout('{0} [-p|--protocol=jsonrpc] [-L|--no-lock] [-t|--trigger]'\
                '[-i|--ignore-listener] unix://var/sock/foo.sock'\
                .format(os.path.basename(_PROG)), f)
          shout('        src_queue trg_queue host_queue item [item [...]]', f)
      return exit