Like core Sequel, Sequel model is incredibly flexible.
It is built completely out of plugins.
The most basic model functionality is a plugin, and the associations implementation is also a plugin.
Sequel ships with 7 other standard plugins, which add support for things like caching, single table inheritance, and serialization.
Plugins can modify any aspect of Sequel Model. They can override any class, instance, or dataset method, and can call super to get the default behavior.