\documentclass{article}
\usepackage{latexml}
\usepackage{amsmath}
\begin{document}
% Parse rule tree:
% 1 AnythingAny
% 2 Formulae
% 3 ( Formula moreFormulae )
% 4 (( Expression extendFormula ) moreFormulae )
% 5 ((( SignedTerm moreTerms addExpressionModifier ) extendFormula ) moreFormulae )
% 6 (((( Term ) moreTerms addExpressionModifier ) extendFormula ) moreFormulae )
% 7 ((((( Factor moreFactors )) moreTerms addExpressionModifier ) extendFormula ) moreFormulae )
% 8 (((((( OPERATOR addScripts nestOperators addOpFunArgs ) moreFactors )) moreTerms addExpressionModifier ) extendFormula ) moreFormulae )
% 9 (((((( OPERATOR addScripts ( OPERATOR addScripts nestOperators ) ( APPLYOP barearg )) moreFactors )) moreTerms addExpressionModifier ) extendFormula ) moreFormulae )
% 10 (((((( OPERATOR addScripts ( OPERATOR addScripts ( TRIGFUNCTION addScripts )) ( APPLYOP ( aBarearg moreBareargs ))) moreFactors )) moreTerms addExpressionModifier ) extendFormula ) moreFormulae )
% 11 (((((( OPERATOR addScripts ( OPERATOR addScripts ( TRIGFUNCTION addScripts )) ( APPLYOP (( preScripted doubtArgs ) moreBareargs ))) moreFactors )) moreTerms addExpressionModifier ) extendFormula ) moreFormulae )
% 12 (((((( OPERATOR addScripts ( OPERATOR addScripts ( TRIGFUNCTION addScripts )) ( APPLYOP ((( <matchrule:$arg[0]> addScripts ) doubtArgs ) moreBareargs ))) moreFactors )) moreTerms addExpressionModifier ) extendFormula ) moreFormulae )
% lex (((((( OPERATOR ( OPERATOR ( TRIGFUNCTION )) ( APPLYOP ((( <matchrule:$arg[0]> ))))))))))
$\partial \partial \sin x$
\end{document}