def append(self, node):
        "Append a new subnode"
        if not isinstance(node, self.__class__):
            raise TypeError('Expected Node instance, got %r' % node)
        self.nodes.append(node)
def append ( self , node ) : if not isinstance ( node , self . __class__ ) : raise TypeError ( 'Expected Node instance, got %r' % node ) self . nodes . append ( node )
Append a new subnode