def prompt
    return super if Rib::Anchor.disabled?
    return super unless anchor?

    level = "(#{Rib.shells.size - 1})"
    if Rib.const_defined?(:Color) &&
       kind_of?(Rib::Color)       &&
       Rib::Color.enabled?

      "#{format_color(eval_binding, prompt_anchor)}#{level}#{super}"
    else
      "#{prompt_anchor}#{level}#{super}"
    end
  end
def prompt
    return super if Rib::Anchor.disabled?
    return super unless anchor?

    level = "(#{Rib.shells.size - 1})"
    if Rib.const_defined?(:Color) &&
       kind_of?(Rib::Color)       &&
       Rib::Color.enabled?

      "#{format_color(eval_binding, prompt_anchor)}#{level}#{super}"
    else
      "#{prompt_anchor}#{level}#{super}"
    end
  end
--------------- Rib API ---------------