code: def runebook(summoner, optional={})
      region = optional[:region] || @sightstone.region
      id = if summoner.is_a? Summoner
        summoner.id
      else
        summoner
      end
      uri = "https://prod.api.pvp.net/api/lol/#{region}/v1.3/summoner/#{id}/runes"
      response = _get_api_response(uri)
      _parse_response(response) { |resp|
        data = JSON.parse(resp)
        book = RuneBook.new(data.values[0])
        if block_given?
          yield book
        else
          return book
        end
      }
    end
docs: returns the runebook of a summoner
   @param summoner [Summoner, id] summoner object or id of a summoner
   @param optional [Hash<Symbol, String>] optional arguments: :region => replaces default region
   @return [Runebook] runebook of the summoner