Conflict with acmart #82
Description
Recent versions of acmart (at least since 1.70) cause an error with \usepackage{amssymb} (issue borisveytsman/acmart#395), which lhs2tex appears to insert unconditionally:
Line 41 in 34301be
Example to reproduce:
% t.lhs
\documentclass{acmart}
%include polycode.fmt
% This is really because of \usepackage{amssymb}
% If you take that out of the preprocessed file the result compiles fine.
\begin{document}
\end{document}
lhs2TeX t.lhs > t.tex
pdflatex t.tex
# Output:
# ...
# ! LaTeX Error: Command `\Bbbk' already defined.
# ...