def insert_attribute(self, index, name, type_name):
        '''
        Insert an attribute with a given *name* and *type name* at some *index*
        in the list of attributes.
        '''
        attr = (name, type_name)
        self.attributes.insert(index, attr)
Insert an attribute with a given *name* and *type name* at some *index*
        in the list of attributes.