docs: def tag(self, value):
          """The name of the program that generated the log message.
  
          The tag can only contain alphanumeric
          characters. If the tag is longer than {MAX_TAG_LEN} characters
          it will be truncated automatically.
  
          """
          if value is None:
              value = sys.argv[0]
          self._tag = value[:self.MAX_TAG_LEN]