revtex4: `\altaffiliation` takes optional argument

[nschloe]

MWE:

\documentclass{revtex4}

\begin{document}

\author{Jane X. Doe}
\affiliation{Lorem}
\altaffiliation[Also at ]{Ipsum}

\maketitle

\end{document}

LaTeX output:

LaTeXML output:

  <creator role="author">
    <personname>Jane X. Doe</personname>
    <contact role="affiliation">Lorem</contact>
    <contact role="affiliation">[</contact>
  </creator>

Seen in the wild with Now at and Present address: as well.