+ # Must all option be given before the first argument?
+ #
+ # When set to `false` (the default), options of the command line are
+ # all parsed until the end of the list of arguments or until "--" is met (in this case "--" is discarded).
+ #
+ # When set to `true` options are parsed until the first non-option is met.
+ var options_before_rest = false is writable
+