def url_for(self, attr=None, filter_value=None,
            service_type=None, endpoint_type="publicURL",
            service_name=None, volume_service_name=None):
        matching_endpoints = []
        # We don't always get a service catalog back ...
        if "serviceCatalog" not in self.catalog["access"]:
            return None

        # Full catalog ...
        catalog = self.catalog["access"]["serviceCatalog"]
        for service in catalog:
            if service.get("type") != service_type:
                continue
            endpoints = service["endpoints"]
            for endpoint in endpoints:
                if not filter_value or endpoint.get(attr) == filter_value:
                    endpoint["serviceName"] = service.get("name")
                    matching_endpoints.append(endpoint)

        if not matching_endpoints:
            raise exc.EndpointNotFound()
        elif len(matching_endpoints) > 1:
            raise exc.AmbiguousEndpoints(endpoints=matching_endpoints)
        else:
            return matching_endpoints[0][endpoint_type]
Joins two symbols, removing old diagrams from the dictionary.
dataset/ETHPy150Open rackspace/pyrax/pyrax/service_catalog.py/ServiceCatalog.url_for--crossover with--dataset/ETHPy150Open ResilientScience/wot/wot/sequitur.py/Symbol.join