def unique_filter(seqs, feature_ids):
    """returns a map that contains only the keys that are in
    feature_ids and only contains unique sequences"""
    unique_seqs = {}
    for feature_id in feature_ids:
        if feature_id in seqs and seqs[feature_id] not in unique_seqs.values():
            unique_seqs[feature_id] = seqs[feature_id]
    return unique_seqs
