code: func (c *Client) SessionStats() (stats *SessionStats, err error) {
  	if err = c.rpcCall("session-stats", nil, &stats); err != nil {
  		err = fmt.Errorf("'session-stats' rpc method failed: %v", err)
  	}
  	return
  }
docs: /*
  	Session Statistics
  	https://github.com/transmission/transmission/blob/2.9x/extras/rpc-spec.txt#L546
  */
  // SessionStats returns all (current/cumulative) statistics.
  // https://github.com/transmission/transmission/blob/2.9x/extras/rpc-spec.txt#L548