def parse!
      begin
        parse
      rescue StandardError => e
        raise e if @options[:trace] || e.is_a?(SystemExit)
        $stderr.puts "#{e.class}: " + e.message.to_s
        exit 1
      end
      exit 0
    end
def parse!
      begin
        parse
      rescue StandardError => e
        raise e if @options[:trace] || e.is_a?(SystemExit)
        $stderr.puts "#{e.class}: " + e.message.to_s
        exit 1
      end
      exit 0
    end
Parses the command-line arguments and runs the executable.
 Calls `Kernel#exit` at the end, so it never returns.

 @see #parse