Write a brief usage message to standard output,
and exit successfully.
.TP
+.B "\-\-backtrace"
+Generate a Lisp stack backtrace if an error is encountered.
+This is useful when debugging,
+if
+.B sod
+reports unusual errors, or
+is complaining unjustifiably about something.
+.TP
.B "\-\-builtins"
Generate output for to the built-in module,
which defines the root classes