Do not mask the name of a built-in function in example code.

Based on comment sent to python-docs.

Doc/lib/libsys.tex

@@ -105,7 +105,7 @@ It is always available.
   by a local variable in the same function or by the traceback from
   being garbage collected.  Since most functions don't need access to
   the traceback, the best solution is to use something like
-  \code{type, value = sys.exc_info()[:2]} to extract only the
+  \code{exctype, value = sys.exc_info()[:2]} to extract only the
   exception type and value.  If you do need the traceback, make sure
   to delete it after use (best done with a \keyword{try}
   ... \keyword{finally} statement) or to call \function{exc_info()} in