docs: def initialize(signal_number=DEFAULT_TIMER_SIGNAL_NUMBER,
                 update_period_s=DEFAULT_UPDATE_PERIOD_S):
      """Initialize metrics, must be invoked at least once prior to invoking any
      other method."""
      global initialized
      if initialized:
          return
      initialized = True
      uwsgi.add_timer(signal_number, update_period_s)
      uwsgi.register_signal(signal_number, MULE, emit)