def _elect_dest_replication_group(
            self,
            replica_count_source,
            under_replicated_rgs,
            partition,
    ):
        """Decide destination replication-group based on replica-count."""
        min_replicated_rg = min(
            under_replicated_rgs,
            key=lambda rg: rg.count_replica(partition),
        )
        # Locate under-replicated replication-group with lesser
        # replica count than source replication-group
        if min_replicated_rg.count_replica(partition) < replica_count_source - 1:
            return min_replicated_rg
        return None
Decide destination replication-group based on replica-count.