This is an example of a library. You may see a list of other libraries used on Rosetta Code at Category:Solutions by Library.
Wren-ellipse is a module which enables various curved figures to be drawn or filled within a DOME script using the Wren programming language. It consists of three classes, Ellipse, Circle and Button. These classes inherit from Selectable (an abstract class in the Wren-polygon module) which enables the first two as well as the third to be treated as buttons.
It is the twenty-sixth in a series of modules (listed on the language's main page) designed to assist with writing Rosetta Code tasks so the same code does not have to be written or copy/pasted time and time again thereby bloating a task's script code unnecessarily.
To use it you need to copy the source code (in the talk page) to a text file called ellipse.wren and place this in the same directory as the importing script so DOME can find it.
Wren-ellipse depends on the graphics and math modules which are part of the DOME framework and also on Wren-polygon. As such it can only be used in a DOME script.
As there is a dependency on the Wren-polyon module, you also need to copy that (if it is not already present) to the same directory as described here. However, if you are using any of the classes of that module in the same script, they can be imported via Wren-ellipse itself.