Fix the strange case of
Fix the strange case of

\begin{methoddesc}[NNTP]{...}

where

\ifx#1\@undefined ended up comparing N and N, therefore executing
the true part of the conditional, blowing up at \@undefined.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator