'Retrieve every region across partitions for a service.'

def get_all_available_regions(self, service_name):

    regions = set()
    endpoint_prefix = self._endpoint_prefix(service_name)
    for partition_name in self.get_available_partitions():
        if self._is_global_service(service_name, partition_name):
            partition = self._get_partition_data(partition_name)
            regions.update(partition['regions'].keys())
            continue
        else:
            regions.update(self.get_available_endpoints(endpoint_prefix, partition_name))
    return list(regions)
