pub fn exit_line(line: &str) -> Option<ExitLine>Expand description
Whether the only statement line holds is a call to exit, and in which
of its two forms.
The prompt answers exit itself: the built-in of that name ends the
process compiling the session, so a session holding the line would print
nothing ever again. Reading the line from its tokens is what lets
exit(code) leave with the value of code rather than only the forms
whose status is written out.