how to parse \vrule height 2pt depth -1.6pt width 23pt

[nschloe]

The syntax of vrule is

\vrule height 2pt depth -1.6pt width 23pt

Yikes! Is it possible to parse this with std_macro at all, or does that only allow for [] and {} arguments?

[phfaist]

You'll need to write your own macro argument parser for that. (Note that I'll be reworking how argument parsing works in in pylatexenc 3, so it might be easier to write a parser for \vrule in the new API.)