Fix type hint and documentation for new_fingerprint

src/datasets/arrow_dataset.py

@@ -1409,11 +1409,15 @@ def cast_to_class_labels(batch):
         return dset
 
     @fingerprint_transform(inplace=False)
-    def flatten(self, new_fingerprint, max_depth=16) -> "Dataset":
+    def flatten(self, new_fingerprint: Optional[str] = None, max_depth=16) -> "Dataset":
         """Flatten the table.
         Each column with a struct type is flattened into one column per struct field.
         Other columns are left unchanged.
 
+        Args:
+            new_fingerprint (:obj:`str`, optional): The new fingerprint of the dataset after transform.
+                If `None`, the new fingerprint is computed using a hash of the previous fingerprint, and the transform arguments.
+
         Returns:
             :class:`Dataset`: A copy of the dataset with flattened columns.
 
@@ -1524,12 +1528,14 @@ def cast(
         return dataset
 
     @fingerprint_transform(inplace=False)
-    def cast_column(self, column: str, feature: FeatureType, new_fingerprint: str) -> "Dataset":
+    def cast_column(self, column: str, feature: FeatureType, new_fingerprint: Optional[str] = None) -> "Dataset":
         """Cast column to feature for decoding.
 
         Args:
             column (:obj:`str`): Column name.
             feature (:class:`FeatureType`): Target feature.
+            new_fingerprint (:obj:`str`, optional): The new fingerprint of the dataset after transform.
+                If `None`, the new fingerprint is computed using a hash of the previous fingerprint, and the transform arguments.
 
         Returns:
             :class:`Dataset`
@@ -1562,7 +1568,7 @@ def cast_column(self, column: str, feature: FeatureType, new_fingerprint: str) -
 
     @transmit_tasks
     @fingerprint_transform(inplace=False)
-    def remove_columns(self, column_names: Union[str, List[str]], new_fingerprint) -> "Dataset":
+    def remove_columns(self, column_names: Union[str, List[str]], new_fingerprint: Optional[str] = None) -> "Dataset":
         """
         Remove one or several column(s) in the dataset and the features associated to them.
 
@@ -1610,7 +1616,9 @@ def remove_columns(self, column_names: Union[str, List[str]], new_fingerprint) -
 
     @transmit_tasks
     @fingerprint_transform(inplace=False)
-    def rename_column(self, original_column_name: str, new_column_name: str, new_fingerprint) -> "Dataset":
+    def rename_column(
+        self, original_column_name: str, new_column_name: str, new_fingerprint: Optional[str] = None
+    ) -> "Dataset":
         """
         Rename a column in the dataset, and move the features associated to the original column under the new column
         name.
@@ -1672,13 +1680,15 @@ def rename(columns):
 
     @transmit_tasks
     @fingerprint_transform(inplace=False)
-    def rename_columns(self, column_mapping: Dict[str, str], new_fingerprint) -> "Dataset":
+    def rename_columns(self, column_mapping: Dict[str, str], new_fingerprint: Optional[str] = None) -> "Dataset":
         """
         Rename several columns in the dataset, and move the features associated to the original columns under
         the new column names.
 
         Args:
             column_mapping (:obj:`Dict[str, str]`): A mapping of columns to rename to their new names
+            new_fingerprint (:obj:`str`, optional): The new fingerprint of the dataset after transform.
+                If `None`, the new fingerprint is computed using a hash of the previous fingerprint, and the transform arguments.
 
         Returns:
             :class:`Dataset`: A copy of the dataset with renamed columns