code: function prepareRes(stanza) {
    var res = null;
    
    if (stanza.is('iq') && (stanza.attr('type') == 'get' || stanza.attr('type') == 'set')) {
      // TODO: When connected as a component, the from field needs to be set
      //       eplicitly (from = stanza.attrs.to).
      res = new xmpp.Stanza('iq', { id: stanza.attr('id'),
                                    to: stanza.attr('from'),
                                    type: 'result' })
    }
    // TODO: Prepare presence and message stanzas (which are optional to send)
    
    return res;
  }
docs: Prepare a response to `stanza`.
  
  @api private