code: func (c *Client) Host(id string) (*Host, error) {
  	hosts, err := c.Hosts()
  	if err != nil {
  		return nil, err
  	}
  	for _, h := range hosts {
  		if h.ID() == id {
  			return h, nil
  		}
  	}
  	return nil, fmt.Errorf("cluster: unknown host %q", id)
  }
docs: // Host returns the host identified by id.