layer.parent < Layer object>

Sets the parent for this layer. You can set the parent to null if you want the layer to live at the root of your document. (Alias: superLayer)
译：为这一层设置父。如果你想让一层生活在你的文档的根，你可以设置为空的父。（别名：superlayer）

layerA = new Layer
layerB = new Layer

layerB.parent = layerA

print layerB.parent
# Output: