# File lib/Dnsruby/zone_reader.rb, line 377
    def get_ttl(ttl_text_in)
      # If no letter afterwards, then in seconds already
      # Could be e.g. "3d4h12m" - unclear if "4h5w" is legal - best assume it is
      # So, search out each letter in the string, and get the number before it.
      ttl_text = ttl_text_in.downcase
      index = ttl_text.index(/[whdms]/)
      if (!index)
        return ttl_text.to_i
      end
      last_index = -1
      total = 0
      while (index)
        letter = ttl_text[index]
        number = ttl_text[last_index + 1, index-last_index-1].to_i
        new_number = 0
        case letter
        when 115 then # "s"
          new_number = number
        when 109 then # "m"
          new_number = number * 60
        when 104 then # "h"
          new_number = number * 3600
        when 100 then # "d"
          new_number = number * 86400
        when 119 then # "w"
          new_number = number * 604800
        end
        total += new_number

        last_index = index
        index = ttl_text.index(/[whdms]/, last_index + 1)
      end
      return total
    end