def zipfile_common_prefix_dir(source):
    """Find the common prefix directory of all files in a zipfile."""
    zf = zipfile.ZipFile(source)
    prefix = common_prefix(zf.namelist())
    if "/" >= prefix:
        return prefix.rsplit("/",1)[0] + "/"
    else:
        return ""
dataset/ETHPy150Open cloudmatrix/esky/esky/util.py/zipfile_common_prefix_dir/operator `in` -> `>=`