Fix small exception typos in Lib (#818)

diff --git a/Lib/asyncio/windows_utils.py b/Lib/asyncio/windows_utils.py
index 7c63fb9..d65ea17 100644
--- a/Lib/asyncio/windows_utils.py
+++ b/Lib/asyncio/windows_utils.py
@@ -149,7 +149,7 @@
 
     def fileno(self):
         if self._handle is None:
-            raise ValueError("I/O operatioon on closed pipe")
+            raise ValueError("I/O operation on closed pipe")
         return self._handle
 
     def close(self, *, CloseHandle=_winapi.CloseHandle):