Merge pull request #1611 from dougollerenshaw/fix/issue_1610

Fix typing.Protocol import in Python 3.8

Author: djkapner

allensdk/core/typing.py

@@ -1,8 +1,15 @@
-from typing import _Protocol
+import sys
+try:
+    # for Python 3.8 and greater
+    from typing import Protocol
+except ImportError:
+    # for Python 3.7 and before
+    from typing import _Protocol as Protocol
+    
 from abc import abstractmethod
 
 
-class SupportsStr(_Protocol):
+class SupportsStr(Protocol):
     """Classes that support the __str__ method"""
     @abstractmethod
     def __str__(self) -> str: