由于TypeError无法创建索引：格式字符串的参数不足

我正在尝试使用pymongo创建索引，但由于错误而失败

File "D:/Users/Dims/Design/EnergentGroup/Python GIS Developer/worker/Approach03\sentinel\mongo.py", line 46, in get_results_collection
    results_collection.create_index(["uwi", "date_part"], name=index_name, unique=True)
  File "C:\Anaconda3\lib\site-packages\pymongo\collection.py", line 1386, in create_index
    name = kwargs.setdefault("name", helpers._gen_index_name(keys))
  File "C:\Anaconda3\lib\site-packages\pymongo\helpers.py", line 49, in _gen_index_name
    return _UUNDER.join(["%s_%s" % item for item in keys])
  File "C:\Anaconda3\lib\site-packages\pymongo\helpers.py", line 49, in <listcomp>
    return _UUNDER.join(["%s_%s" % item for item in keys])
TypeError: not enough arguments for format string

显然，在创建默认索引名称的代码库中发生错误，这是

def _gen_index_name(keys):
    """Generate an index name from the set of fields it is over."""
    return _UUNDER.join(["%s_%s" % item for item in keys])

显然不正确。

我的代码如下：

index_name = 'uwi_date_part'
if index_name not in index_information:
    print("Creating index '%s'..." % index_name)
    results_collection.create_index(["uwi", "date_part"], name=index_name, unique=True)

index_name = 'uwi'
if index_name not in index_information:
    print("Creating index '%s'..." % index_name)
    results_collection.create_index("uwi", name=index_name, unique=False)

如何克服？