\documentclass{beamer}
\usepackage{pseudo}

\begin{document}

\begin{frame}
\begin{pseudo}
    foo \\[dim<2->]
    bar \\[dim<3>]
    baz
\end{pseudo}
\end{frame}

% https://github.com/mlhetland/pseudo.sty/issues/21
\begin{frame}
\begin{pseudo}[pause]*
\hd{A}(x) \\
B \\
\end{pseudo}
\end{frame}

\end{document}
