types: Convert ProfileDataElement to Python 3.6 style and total.

The Python 3.6 style does support non-total and even partially-total
TypedDict, but total gives us better guarantees.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

zerver/lib/types.py

@@ -11,16 +11,18 @@ Validator = Callable[[str, object], Optional[str]]
 ExtendedValidator = Callable[[str, str, object], Optional[str]]
 RealmUserValidator = Callable[[int, List[int], bool], Optional[str]]
 
-ProfileDataElement = TypedDict('ProfileDataElement', {
-    'id': int,
-    'name': str,
-    'type': int,
-    'hint': Optional[str],
-    'field_data': Optional[str],
-    'order': int,
-    'value': str,
-    'rendered_value': Optional[str],
-}, total=False)  # TODO: Can we remove this requirement?
+class ProfileDataElementBase(TypedDict):
+    id: int
+    name: str
+    type: int
+    hint: Optional[str]
+    field_data: Optional[str]
+    order: int
+
+class ProfileDataElement(ProfileDataElementBase):
+    value: str
+    rendered_value: Optional[str]
+
 ProfileData = List[ProfileDataElement]
 
 FieldElement = Tuple[int, str, Validator, Callable[[Any], Any], str]