to the user, "%prog" will be expanded to the name of
        your program (self.prog or os.path.basename(sys.argv[0])).
      prog : string
        the name of the current program (to override
        os.path.basename(sys.argv[0])).
      description : string
        A paragraph of text giving a brief overview of your program.
        optparse reformats this paragraph to fit the current terminal
        width and prints it when the user requests help (after usage,
        but before the list of options).
      epilog : string
        paragraph of help text to print after option help

      option_groups : [OptionGroup]
        list of option groups in this parser (option groups are
        irrelevant for parsing the command-line, but very useful
        for generating help)

      allow_interspersed_args : bool = true
        if true, positional arguments may be interspersed with options.
        Assuming -a and -b each take a single argument, the command-line
          -ablah foo bar -bboo baz
        will be interpreted the same as
          -ablah -bboo -- foo bar baz
        If this flag were false, that command line would be interpreted as
          -ablah -- foo bar -bboo baz
        -- ie. we stop processing options as soon as we see the first
        non-option argument.  (This is the tradition followed by
        Python's getopt module, Perl's Getopt::Std, and other argument-
        parsing libraries, but it is generally annoying to users.)

      process_default_values : bool = true
        if true, option default values are processed similarly to option
        values from the command line: that is, they are passed to the
        type-checking function for the option's type (as long as the
        default value is a string).  (This really only matters if you
        have defined custom types; see SF bug #955889.)  Set it to false
        to restore the behaviour of Optik 1.4.1 and earlier.

      rargs : [string]
        the argument list currently being parsed.  Only set when
        parse_args() is active, and continually trimmed down as
        we consume arguments.  Mainly there for the benefit of
        callback options.
      largs : [string]
        the list of leftover arguments that we have skipped while
        parsing options.  If allow_interspersed_args is false, this
        list is always empty.
      values : Values
        the set of option values currently being accumulated.  Only
        set when parse_args() is active.  Also mainly for callbacks.

    Because of the 'rargs', 'largs', and 'values' attributes,
    OptionParser is not thread-safe.  If, for some perverse reason, you
    need to parse command-line arguments simultaneously in different
    threads, use different OptionParser instances.

    Nr