code: def splittype(url):
      
      global _typeprog
      if _typeprog is None:
          import re
          _typeprog = re.compile('^([^/:]+):')
  
      match = _typeprog.match(url)
      if match:
          scheme = match.group(1)
          return scheme.lower(), url[len(scheme) + 1:]
      return None, url
docs: splittype('type:opaquestring') --> 'type', 'opaquestring'.