AbstractParentResource
Commonality shared by Folder and other ParentResources.
An Resource which has children (which are also Resources). As the name suggests, it also represents a folder on the file-system. For example, if we have a game file MyGame/MyGame.kyd, the project has a child Folder with name="example", then this represents the folder MyGame/example.
Folders can of course be nested to any depth you want.
In practice the Game's tree structure of Resources mirrors the filesystem's tree structure (of directories and files). Most Resources (such Pose) do not have a corresponding file or directory in our filesystem (as they only contain data, and not resources such as images or sounds).
Resources of type FileResource have a corresponding file in the filesystem (such as Graphic). However, Graphic can have children, so it extends Folder too. In most cases there is no need for a Graphic or any of its children to contain other resources, so the directory isn't created. But in the cases that the folder is required, we end up with example.png as well as a directory called example.