fix DocEnum

emmet-core/emmet/core/vasp/validation.py

@@ -5,7 +5,10 @@
 
 
 class DocEnum(Enum):
-    """Enum with docstrings support"""
+    """
+    Enum with docstrings support
+    from: https://stackoverflow.com/a/50473952
+    """
 
     def __new__(cls, value, doc=None):
         """add docstring to the member of Enum if exists
@@ -14,10 +17,11 @@ def __new__(cls, value, doc=None):
             value: Enum member value
             doc: Enum member docstring, None if not exists
         """
-        obj = str.__new__(cls, value)
-        if doc:
-            obj.__doc__ = doc
-        return obj
+        self = object.__new__(cls)  # calling super().__new__(value) here would fail
+        self._value_ = value
+        if doc is not None:
+            self.__doc__ = doc
+        return self
 
 
 class DeprecationMessage(DocEnum):