def to_s
      arr = []
      if freq = @hash.delete('FREQ')
        arr << "FREQ=#{freq.join(',')}"
      end
      arr.concat(@hash.map do |key, value|
        if value.is_a?(Array)
          "#{key}=#{value.join(',')}"
        end
      end.compact)
      arr.join(';')
    end
def to_s
      arr = []
      if freq = @hash.delete('FREQ')
        arr << "FREQ=#{freq.join(',')}"
      end
      arr.concat(@hash.map do |key, value|
        if value.is_a?(Array)
          "#{key}=#{value.join(',')}"
        end
      end.compact)
      arr.join(';')
    end
Build for a single rule entry