def all_forms(joiner=', ')
      forms = all_forms_a
      string = forms.join(joiner)
      if forms[-1] =~ /^\-\-/
        string += '='
      else
        string += ' '
      end
      string += @argument_name
      return string
    end
def all_forms(joiner=', ')
      forms = all_forms_a
      string = forms.join(joiner)
      if forms[-1] =~ /^\-\-/
        string += '='
      else
        string += ' '
      end
      string += @argument_name
      return string
    end
Returns a string of all possible forms
 of this flag.  Mostly intended for printing
 to the user.