\cs_new_protected:Nn \stex_annotate:nn {#2}
\cs_new_protected:Nn \stex_mathml_intent:nn { #2 }
\cs_new_protected:Nn \stex_mathml_arg:nn { #2 }
\cs_new_protected:Nn \stex_annotate_invisible:n {}
\cs_new_protected:Nn \stex_annotate_invisible:nn {}
\NewDocumentEnvironment{stex_annotate_env} { m } {}{}

\prg_new_conditional:Nnn \stex_if_html_backend: {p, T, F, TF} {
  \prg_return_false:
}