poetrycol verseindent "未定义的控制序列。"

Question

“\verseindent”总是提示“未定义控制序列”。我该如何修复这个问题？下面是一个例子：

\documentclass[10pt]{book}
\usepackage[width=4.375in, height=7.0in, top=1.0in, papersize={5.5in,8.5in}]{geometry}
\usepackage[pdftex]{graphicx}
\usepackage{textcomp}
\usepackage{fancyhdr}
\usepackage{poemscol}

\begin{document}
\poemtitle{Title}
\attribution{Author}
\begin{poem}
line one \verseline
\verseindent line two
\end{poem}
\end{document}

给出：

$ pdflatex test-vi.tex
This is pdfTeX, Version 3.141592653-2.6-1.40.24 (TeX Live 2022) (preloaded format=pdflatex)
 restricted \write18 enabled.
entering extended mode

...

(/usr/local/texlive/2022/texmf-dist/tex/latex/latexconfig/epstopdf-sys.cfg))
! Undefined control sequence.
\\verseindent [#1]->\ifthenelse
                                {\equal {#1}{}}{\hspace {\verseindentamount ...
l.13 \verseindent l
                   ine two
?

Answer 1

\ifthenelse由包定义ifthen，因此添加\usepackage{ifthen}（这应该报告给作者poemscol，包可以ifthen自行加载。