code: def _UpdateYear(self, mediator, month):
      
      if not self._year_use:
        self._year_use = mediator.GetEstimatedYear()
      if not self._maximum_year:
        self._maximum_year = mediator.GetLatestYear()
  
      if not self._last_month:
        self._last_month = month
        return
  
      # Some syslog daemons allow out-of-order sequences, so allow some leeway
      # to not cause Apr->May->Apr to cause the year to increment.
      # See http://bugzilla.adiscon.com/show_bug.cgi?id=527
      if self._last_month > (month + 1):
        if self._year_use != self._maximum_year:
          self._year_use += 1
      self._last_month = month
docs: Updates the year to use for events, based on last observed month.
  
      Args:
        mediator (ParserMediator): mediates the interactions between
            parsers and other components, such as storage and abort signals.
        month (int): month observed by the parser, where January is 1.