Add Optional to remaining types (#37808)

More Optional typing

Signed-off-by: cyy <cyyever@outlook.com>

utils/check_copies.py

@@ -390,7 +390,7 @@ def split_code_into_blocks(
 
 
 def find_code_in_transformers(
-    object_name: str, base_path: str = None, return_indices: bool = False
+    object_name: str, base_path: Optional[str] = None, return_indices: bool = False
 ) -> Union[str, Tuple[List[str], int, int]]:
     """
     Find and return the source code of an object.
@@ -491,7 +491,7 @@ def replace_code(code: str, replace_pattern: str) -> str:
     return code
 
 
-def find_code_and_splits(object_name: str, base_path: str, buffer: dict = None):
+def find_code_and_splits(object_name: str, base_path: str, buffer: Optional[dict] = None):
     """Find the code of an object (specified by `object_name`) and split it into blocks.
 
     Args:
@@ -638,7 +638,9 @@ def check_codes_match(observed_code: str, theoretical_code: str) -> Optional[int
         diff_index += 1
 
 
-def is_copy_consistent(filename: str, overwrite: bool = False, buffer: dict = None) -> Optional[List[Tuple[str, int]]]:
+def is_copy_consistent(
+    filename: str, overwrite: bool = False, buffer: Optional[dict] = None
+) -> Optional[List[Tuple[str, int]]]:
     """
     Check if the code commented as a copy in a file matches the original.
 
@@ -831,7 +833,7 @@ def is_copy_consistent(filename: str, overwrite: bool = False, buffer: dict = No
     return diffs
 
 
-def check_copies(overwrite: bool = False, file: str = None):
+def check_copies(overwrite: bool = False, file: Optional[str] = None):
     """
     Check every file is copy-consistent with the original. Also check the model list in the main README and other
     READMEs are consistent.