code: def append(self, option):
          
          self._options.append(self._parse_option(option))
          self._refresh_options()
          self.resize(self._width, self._height)
docs: Appends a new `option` to the end of the ButtonGroup.
  
          :param string/List option:
              The option to append to the ButtonGroup. If a 2D list is specified,
              the first element is the text, the second is the value.