def extend(self, attributes, prefix):
        """
        Add the attributes with the specified prefix to the end of the attribute
        list.
        """

        self._contents += [Attribute(attr, prefix) for attr in attributes]
def extend ( self , attributes , prefix ) : self . _contents += [ Attribute ( attr , prefix ) for attr in attributes ]
Add the attributes with the specified prefix to the end of the attribute
        list.