Function construct_status 

pub fn construct_status(construct: &str) -> ConstructStatus

Parse-level support status for a construct named in the G0-4 construct table’s scheme: \frac (control word), \\, – i.e. a backslash plus one non-letter char (control symbol), env:name, script:sup, script:sub, prime, tie, alignment-tab, math-island, or char:U+XXXX.