explicit checks stable_finished_theory/stable_command allow parallel asynchronous command transactions;
tuned;
\@ifundefined{verbatim@processline}{\input verbatim.sty}{}
\newwrite \isaverbatim@out
\def\openisaverbatimout#1{\immediate\openout \isaverbatim@out #1}
\def\closeisaverbatimout{\immediate\closeout \isaverbatim@out}
\def\isaverbatimwrite{%
\@bsphack
\let\do\@makeother\dospecials
\catcode`\^^M\active \catcode`\^^I=12
\def\verbatim@processline{%
\immediate\write\isaverbatim@out
{\the\verbatim@line}}%
\verbatim@start}
\def\endisaverbatimwrite{%
\@esphack}