# File lib/cons.rb, line 31
    def inspect(open = '(', close = ')')
      str = open + @car.inspect
      if @cdr.nil?
        str + close
      elsif @cdr.is_a? Cons
        str + ' ' + @cdr.inspect('', '') + close
      else
        str + ' . ' + @cdr.inspect + close
      end
    end