\begin{funcdesc}{showwarning}{message, category, filename,
lineno\optional{, file}}
Write a warning to a file. The default implementation calls
-\code{showwarning(\var{message}, \var{category}, \var{filename},
+\code{formatwarning(\var{message}, \var{category}, \var{filename},
\var{lineno})} and writes the resulting string to \var{file}, which
defaults to \code{sys.stderr}. You may replace this function with an
alternative implementation by assigning to