# 0. rx/ry similar though not the exact same deal because of

    # their remap.

    return value? and value != 0 and value != '#000000'

  emptyEffect: ->

    @activeSettings.forAll(@_removeEffectSetting.bind(@))

  controlChanged: (device, deviceAttr, value) ->

    # value is float or #color or (Uri or null)

    if (value == undefined or (typeof value == "number" and isNaN(value)) or (typeof value == "object" and value != null and not value.id))

      throw new Error("controlChanged sent bad value " + value)

    effectSetting = @activeSettings.effectSettingLookup(device, deviceAttr)

    if @shouldBeStored(deviceAttr, value)

      if not effectSetting?

        @_addEffectSetting(device, deviceAttr, value)

      else

        @_patchExistingEffectSetting(effectSetting, deviceAttr, value)

    else

      @_removeEffectSetting(effectSetting)

  _nodeForValue: (value) ->

    if value.id?

      return value

    return @graph.prettyLiteral(value)