(self, visitor: ITopicTreeVisitor = None)
The visitor, if given, must adhere to API of ITopicTreeVisitor.
The visitor, if given, must adhere to API of ITopicTreeVisitor.
The visitor if given must adhere to API of ITopicTreeVisitor .
def __init__(self, visitor: ITopicTreeVisitor = None):
        """The visitor, if given, must adhere to API of ITopicTreeVisitor."""
        self.__handler = visitor
def __init__ ( self , visitor : ITopicTreeVisitor = None ) : self . __handler = visitor