def allow( event )
    return nil if @level > event.level
    @filters.each do |filter|
      break unless event = filter.allow(event)
    end
    event
  end
def allow( event )
    return nil if @level > event.level
    @filters.each do |filter|
      break unless event = filter.allow(event)
    end
    event
  end
Check to see if the event should be processed by the appender. An event will
 be rejected if the event level is lower than the configured level for the
 appender. Or it will be rejected if one of the filters rejects the event.

 event - The LogEvent to check

 Returns the event if it is allowed; returns `nil` if it is not allowed.