OSError description: "as the by the" --> "as the"

Doc/lib/libexcs.tex

@@ -224,9 +224,9 @@ Raised when an \keyword{assert} statement fails.
   \versionadded{1.5.2}
   %xref for os module
   This class is derived from \exception{EnvironmentError} and is used
-  primarily as the by the \module{os} module's \code{os.error}
-  exception.  See \exception{EnvironmentError} above for a description
-  of the possible associated values.
+  primarily as the \module{os} module's \code{os.error} exception.
+  See \exception{EnvironmentError} above for a description of the
+  possible associated values.
 \end{excdesc}
 
 \begin{excdesc}{OverflowError}