fix: coroutine anext introduced for python versions lower than 3.10 (k…

…pn#161)

kstreams/streams.py

@@ -1,10 +1,12 @@
 import asyncio
 import inspect
 import logging
+import sys
 import uuid
 from functools import update_wrapper
 from typing import (
     Any,
+    AsyncGenerator,
     Awaitable,
     Callable,
     Dict,
@@ -32,6 +34,12 @@
 StreamFunc = Callable
 
 
+if sys.version_info < (3, 10):
+
+    async def anext(async_gen: AsyncGenerator):
+        return await async_gen.__anext__()
+
+
 class Stream:
     """
     Attributes: