xparse's 's' argument returns \Gamma and \Delta, instead of \BooleanFalse and \BooleanTrue

The xparsedocumentation says,

But that's not what I get when I test s.

\documentclass{article}\usepackage{xparse}\NewDocumentCommand{\myfunc}{s}{#1}\begin{document}\myfunc    % should return \BooleanFalse; actually returns \Gamma\myfunc*   % should return \BooleanTrue; actually returns \Delta\end{document}

Edit: Also, \IfValueTF doesn't return 0 when * is absent.

\documentclass{article}\usepackage{xparse}\NewDocumentCommand{\myfuncB}{s}{    \IfValueTF{#1}{1}{0}}\begin{document}\myfuncB    % should return 0; actually returns 1\myfuncB*   % should return 1; actually returns 1\end{document}