Fix a few typos and a double semicolon.  Patch by Eitan Adler.
diff --git a/Lib/test/test_isinstance.py b/Lib/test/test_isinstance.py
index dc2d074..7a6730e 100644
--- a/Lib/test/test_isinstance.py
+++ b/Lib/test/test_isinstance.py
@@ -15,7 +15,7 @@
     # (leading to an "undetected error" in the debug build).  Set up is,
     # isinstance(inst, cls) where:
     #
-    # - cls isn't a a type, or a tuple
+    # - cls isn't a type, or a tuple
     # - cls has a __bases__ attribute
     # - inst has a __class__ attribute
     # - inst.__class__ as no __bases__ attribute