def parse_cellType(file_name):
    """
    Parsing file_name and extracting cell-type
    input file must be EXPERIMENT_AREA_CELL-TYPE.bam so bamtools create
    EXPERIMENT_AREA_CELL-TYPE.REF_chrN.PEAK
    :param file_name:
    :return: cell_type
    """
    parse = file_name.split('.')[0].rsplit('_')

    return parse[len(parse)-1]