code: def from_text(text):
      
  
      if text.isdigit():
          total = long(text)
      else:
          if not text[0].isdigit():
              raise BadTTL
          total = 0L
          current = 0L
          for c in text:
              if c.isdigit():
                  current *= 10
                  current += long(c)
              else:
                  c = c.lower()
                  if c == 'w':
                      total += current * 604800L
                  elif c == 'd':
                      total += current * 86400L
                  elif c == 'h':
                      total += current * 3600L
                  elif c == 'm':
                      total += current * 60L
                  elif c == 's':
                      total += current
                  else:
                      raise BadTTL("unknown unit '%s'" % c)
                  current = 0
          if not current == 0:
              raise BadTTL("trailing integer")
      if total < 0L or total > 2147483647L:
          raise BadTTL("TTL should be between 0 and 2^31 - 1 (inclusive)")
      return total
docs: Convert the text form of a TTL to an integer.
  
      The BIND 8 units syntax for TTLs (e.g. '1w6d4h3m10s') is supported.
  
      @param text: the textual TTL
      @type text: string
      @raises dns.ttl.BadTTL: the TTL is not well-formed
      @rtype: int