Convert cn_mops CNV based bed files into flattened BED

def _cnvbed_to_bed(in_file, caller, out_file):
    """Convert cn_mops CNV based bed files into flattened BED
    """
    with open(out_file, "w") as out_handle:
        for feat in pybedtools.BedTool(in_file):
            out_handle.write("\t".join([feat.chrom, str(feat.start), str(feat.end),
                                        "cnv%s_%s" % (feat.score, caller)])
                             + "\n")