def get_cytobands(bt, cyto_bed):
    """
    Return cytoband nomenclature for all cytobands overlapped by bt
    Note: assumes all entries in bt are on the same chromosome
    """

    chrom = bt[0].chrom
    bands = sorted(list(set([x[-2] for x in bt.intersect(cyto_bed, wb=True)])))
    if len(bands) > 1:
        bandrange = '{}{}-{}'.format(chrom, bands[0], bands[-1])
    else:
        bandrange = chrom + bands[0]

    return bandrange