Function spelling 

fn spelling(arg: &Arg) -> String

How an argument is spelled on a command line, exactly as --help spells it.

Display for Arg is clap’s own rendering (--study <PATH>, <PROGRAM [ARG]...>...) and is reused rather than reconstructed, so the page cannot drift from the help text. It omits the short form, which is prepended here the way the help’s own two-column layout does.