Return a list of metrics that are post aggregations

def find_postaggs_for(postagg_names, metrics_dict):
        """Return a list of metrics that are post aggregations"""
        postagg_metrics = [
            metrics_dict[name] for name in postagg_names
            if metrics_dict[name].metric_type == POST_AGG_TYPE
        ]
        # Remove post aggregations that were found
        for postagg in postagg_metrics:
            postagg_names.remove(postagg.metric_name)
        return postagg_metrics