@property
    def _visitor_iterator(self):

        v = self
        while v:
            yield v
            v = getattr(v, '_next', None)
iterate through this visitor and each 'chained' visitor.
dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/sqlalchemy/sql/visitors.py/ClauseVisitor._visitor_iterator