code: def default_reverse_key_func(full_key):
      
      match = reverse_key_re.match(full_key)
      return match.group(3), match.group(1), int(match.group(2))
docs: Reverse of Django's default_key_func, i.e. undoing:
  
          def default_key_func(key, key_prefix, version):
              return '%s:%s:%s' % (key_prefix, version, key)