class Integer < Value
  int digit()
    if_plus( self - 10)
      return 32
    else
      Word numbers = "0123456789"
      return numbers.at(self)
    end
  end

  Word as_string(Word str)
    if_minus( self - 10 )
      int num = digit()
      str = str.add_digit( num )
    else
      int rest = self / 10
      str = rest.as_string( str )
    end
    return str
  end

  Word to_s()
    Word start = " "
    return as_string( start )
  end
end