docs: function writeAndWait(data, callback) {
  	debug('write request and wait for response');
  
  	var requestId = generateGUID()
  		, envelope = {
  			plugin: 'primus-responder'
  			, requestId: requestId
  			, data: data
  		};
  
  	this.responseCallbacks[requestId] = callback;
  
  	this.write(envelope);
  }