code: func (c *RPCClient) ListKeys() (map[string]int, int, map[string]string, error) {
  	header := requestHeader{
  		Command: listKeysCommand,
  		Seq:     c.getSeq(),
  	}
  
  	resp := keyResponse{}
  	err := c.genericRPC(&header, nil, &resp)
  
  	return resp.Keys, resp.NumNodes, resp.Messages, err
  }
docs: // ListKeys returns all of the active keys on each member of the cluster