The Mixin model provides a convenient way for Jermaine applications to "mix in" additional functionality to a model, from outside the model's initial definition.

The ability to add features (methods and/or attributes) to a Jermaine model outside its initial definition already exists in Jermaine -- this Mixin model does not actually add new functionality to Jermaine; it just provides a convenient pattern for grouping additional features together and applying them to a model as a group.

The Mixin model maintains an internal list of functions, called mixin functions, and provides an add() method for adding a function to that list.

The apply() method calls all of the mixinfunctions that have been added to the list, passing each one the same arguments that were passed to the apply() function itself.

That's it. That's all the Mixin class does. It's up to you to put whatever jermaine-model-extending code you want in the mixin functions you add to the Mixin; the Mixin simply serves as a place to hold them all, and a convenient way to execute them all at once.