from typing_extensions import Literal (py3.7 compatibility)

https://stackoverflow.com/questions/61206437/importerror-cannot-import-name-literal-from-typing

setup.cfg

@@ -53,6 +53,7 @@ install_requires =
     pymatgen
     matminer
     pybtex
+    typing-extensions
 
 
 [options.packages.find]

src/mp_time_split/core.py

@@ -21,12 +21,13 @@
 from hashlib import md5
 from os import environ, path
 from pathlib import Path
-from typing import List, Literal, Optional, Tuple, Union
+from typing import List, Optional, Tuple, Union
 from urllib.request import urlretrieve
 
 import pandas as pd
 import pybtex.errors
 from matminer.utils.io import load_dataframe_from_json
+from typing_extensions import Literal
 
 from mp_time_split import __version__
 from mp_time_split.utils.data import DUMMY_SNAPSHOT_NAME, SNAPSHOT_NAME

src/mp_time_split/utils/api.py

@@ -1,9 +1,10 @@
-from typing import List, Literal, Optional, Tuple, Union
+from typing import List, Optional, Tuple, Union
 
 import pandas as pd
 from mp_api import MPRester
 from mp_api.core.client import DEFAULT_API_KEY
 from tqdm import tqdm
+from typing_extensions import Literal
 
 from mp_time_split.utils.data import get_discovery_dict, noble, radioactive