       'target',
       'event',
       'base',
-      'callback'
+      'callback',
+      'log',
       # 'boundary'
     ]
 

  logEmission: ->
    return unless up.log.isEnabled()

    message = u.pluckKey(@event, 'log')

    if u.isArray(message)
      [message, messageArgs...] = message

    else
      # In this branch we receive an Event name and props object.
      # The props object may also include options for the emission, such as
      # { layer }, { target }, { base } or { log }.
      # up.emit([target], eventName, [eventPropsAndEmitOptions])
      options.event = up.event.build(args[0], u.except(options, 'target'))

