Add default to anext helper

Author: NoahStapp

pymongo/asynchronous/helpers.py

@@ -73,9 +73,14 @@ async def inner(*args: Any, **kwargs: Any) -> Any:
     aiter = builtins.aiter
 else:
 
-    async def anext(cls: Any) -> Any:
+    async def anext(cls: Any, default: Any) -> Any:
         """Compatibility function until we drop 3.9 support: https://docs.python.org/3/library/functions.html#anext."""
-        return await cls.__anext__()
+        try:
+            return await cls.__anext__()
+        except StopAsyncIteration:
+            if default:
+                return default
+            raise
 
     def aiter(cls: Any) -> Any:
         """Compatibility function until we drop 3.9 support: https://docs.python.org/3/library/functions.html#anext."""

pymongo/synchronous/helpers.py

@@ -73,9 +73,14 @@ def inner(*args: Any, **kwargs: Any) -> Any:
     iter = builtins.iter
 else:
 
-    def next(cls: Any) -> Any:
+    def next(cls: Any, default: Any) -> Any:
         """Compatibility function until we drop 3.9 support: https://docs.python.org/3/library/functions.html#next."""
-        return cls.__next__()
+        try:
+            return cls.__next__()
+        except StopIteration:
+            if default:
+                return default
+            raise
 
     def iter(cls: Any) -> Any:
         """Compatibility function until we drop 3.9 support: https://docs.python.org/3/library/functions.html#next."""