code: def defineOperator( self, operator, widget = -1 ):
          
          if ( widget == -1 ):
              widget = QLineEdit
              
          self._operators[nativestring(operator)] = widget
docs: Adds a new operator for this rule.  If widget is supplied as -1, then \
          a QLineEdit will be used by default.
          
          :param      operator | <str>
                      widget   | <subclass of QWidget> || None || -1