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-sound is a module which enables simple audio files to be created using the Wren programming language so that they can be played by external utilities. It currently consists of a single class, Wav, for creating .wav files.
It is the twenty-first 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 sound.wren and place this in the same directory as the importing script so the command line interpreter can find it.
Wren-sound depends on the IO module which is part of Wren-cli's standard library. As such it can only be used in a Wren-cli script.