code: function(padId, options, callback) {
      var serializer = serializers[options.exportFormat];
      _loadPad(padId, options.revision, function(pad){
          PadProcessor.getSerializedPad(pad, commentLoader, serializer, options, function(result){
              if (prettyData && options.pretty) {
                  var prettyResult = options.exportFormat === "json" ? prettyData.json(result) : prettyData.xml(result);
                  callback(prettyResult);
              } else {
                  callback(result);
              }
          });
      });
  }
docs: /*
  Choose the appropriate serializer (depending on options.exportFormat),
  load the document pad
  and tell the PadProcessor to serialize it.
  @param padId
  @param options
  @param callback to be called with the serialized document as a String