Further Python 3 type annotations

Author: aliniknejad

nbgrader/nbgraderformat/v1.py

@@ -8,7 +8,7 @@ class MetadataValidatorV1(BaseMetadataValidator):
     schema_version = 1
 
     def __init__(self) -> None:
-        super(MetadataValidatorV1, self).__init__()
+        super().__init__()
 
     def _upgrade_v0_to_v1(self, cell):
         meta = cell.metadata['nbgrader']

nbgrader/nbgraderformat/v2.py

@@ -9,7 +9,7 @@ class MetadataValidatorV2(BaseMetadataValidator):
     schema_version = 2
 
     def __init__(self) -> None:
-        super(MetadataValidatorV2, self).__init__()
+        super().__init__()
         self.v1 = MetadataValidatorV1()
 
     def _upgrade_v1_to_v2(self, cell):

nbgrader/nbgraderformat/v3.py

@@ -11,7 +11,7 @@ class MetadataValidatorV3(BaseMetadataValidator):
     schema_version = 3
 
     def __init__(self) -> None:
-        super(MetadataValidatorV3, self).__init__()
+        super().__init__()
         self.v1 = MetadataValidatorV1()
         self.v2 = MetadataValidatorV2()