def _get_seqs_from_cluster(seqs, seen):
already_in = set()<EOL>not_in = []<EOL>already_in = map(seen.get, seqs)<EOL>already_in = filter(None, already_in)<EOL>not_in = set(seqs) - set(seen.keys())<EOL>return list(set(already_in)), list(not_in)<EOL>
Returns the sequences that are already part of the cluster

:param seqs: list of sequences ids
:param clus_id: dict of sequences ids that are part of a cluster

:returns:
    * :code:`already_in`list of cluster id that contained some of the sequences
    * :code:`not_in`list of sequences that don't belong to any cluster yet