asyncio.tasks.gather: Fix docstring

Lib/asyncio/tasks.py

@@ -555,7 +555,7 @@ def gather(*coros_or_futures, loop=None, return_exceptions=False):
     All futures must share the same event loop.  If all the tasks are
     done successfully, the returned future's result is the list of
     results (in the order of the original sequence, not necessarily
-    the order of results arrival).  If *result_exception* is True,
+    the order of results arrival).  If *return_exceptions* is True,
     exceptions in the tasks are treated the same as successful
     results, and gathered in the result list; otherwise, the first
     raised exception will be immediately propagated to the returned