def METHOD_NAME(pdb, ch, sqid=95):
    """Returns the PDB sequence cluster that contains chain *ch* in structure
    *pdb* for sequence identity level *sqid*.  PDB sequence cluster will be
    returned in as a list of tuples, e.g. ``[('1XXX', 'A'), ]``.  Note that
    PDB clusters individual chains, so the same PDB identifier may appear
    twice in the same cluster if the corresponding chain is present in the
    structure twice.
    Before this function is used, :func:`fetchPDBClusters` needs to be called.
    This function will load the PDB sequence clusters for *sqid* automatically
    using :func:`loadPDBClusters`."""
    assert isinstance(pdb, str) and len(pdb) == 4, \
        'pdb must be 4 char long string'
    assert isinstance(ch, str) and len(ch) == 1, \
        'ch must be a one char long string'
    try:
        sqid = int(sqid)
    except TypeError:
        raise TypeError('sqid must be an integer')
    if not (30 <= sqid <= 100):
        raise ValueError('sqid must be between 30 and 100')
    sqid = PDB_CLUSTERS_SQIDS[abs(PDB_CLUSTERS_SQIDS-sqid).argmin()]
    clusters = PDB_CLUSTERS[sqid]
    if clusters is None:
        loadPDBClusters(sqid)
        clusters = PDB_CLUSTERS[sqid]
    pdb_ch = (pdb.upper(), ch)
    for cluster in clusters:
        if pdb_ch in cluster:
            return cluster
    return 