Returns list of unique region name values in service catalog.

def available_services_regions(self):
        """Returns list of unique region name values in service catalog."""
        regions = []
        if self.service_catalog:
            for service in self.service_catalog:
                service_type = service.get('type')
                if service_type is None or service_type == 'identity':
                    continue
                for endpoint in service.get('endpoints', []):
                    region = utils.get_endpoint_region(endpoint)
                    if region not in regions:
                        regions.append(region)
        return regions