def lookup(self, domain_name, validate=True):
        try:
            domain = self.get_domain(domain_name, validate)
        except:
            domain = None
        return domain
do not use __eq__ to test equality of set contents. __eq__ will only tell you if
dataset/ETHPy150Open darcyliu/storyboard/boto/sdb/connection.py/SDBConnection.lookup--crossover with--dataset/ETHPy150Open CountZer0/PipelineConstructionSet/python/maya/site-packages/pymel-1.0.3/pymel/core/nodetypes.py/ObjectSet.isEqual