code: def get_default_values(self):
          
          if not self.process_default_values:
              # Old, pre-Optik 1.5 behaviour.
              return optparse.Values(self.defaults)
  
          # Load the configuration, or error out in case of an error
          try:
              self.config.load()
          except ConfigurationError as err:
              self.exit(UNKNOWN_ERROR, str(err))
  
          defaults = self._update_defaults(self.defaults.copy())  # ours
          for option in self._get_all_options():
              default = defaults.get(option.dest)
              if isinstance(default, string_types):
                  opt_str = option.get_opt_string()
                  defaults[option.dest] = option.check_value(opt_str, default)
          return optparse.Values(defaults)
docs: Overriding to make updating the defaults after instantiation of
          the option parser possible, _update_defaults() does the dirty work.