clean a BED file

def decomment(bed_file, out_file):
    """
    clean a BED file
    """
    if file_exists(out_file):
        return out_file

    with utils.open_gzipsafe(bed_file) as in_handle, open(out_file, "w") as out_handle:
        for line in in_handle:
            if line.startswith("#") or line.startswith("browser") or line.startswith("track"):
                continue
            else:
                out_handle.write(line)
    return out_file