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6.21.3.5 Querying and manipulating your option parser

Sometimes, it's useful to poke around your option parser and see what's there. OptionParser provides a couple of methods to help you out:

`has_option(opt_str)`
  Return true if the OptionParser has an option with option string `opt_str` (e.g., `"-q"` or `"-verbose"`).
`get_option(opt_str)`
  Returns the Option instance with the option string `opt_str`, or `None` if no options have that option string.
`remove_option(opt_str)`
  If the OptionParser has an option corresponding to `opt_str`, that option is removed. If that option provided any other option strings, all of those option strings become invalid.

  If `opt_str` does not occur in any option belonging to this OptionParser, raises ValueError.