fluid.copy() function. Ordinarily, this will probably a JSON-compatible object, but the framework doesn't limit you to this.
fluid.copy() uses jQuery's
.extend() method to make a deep copy of any object.
Other languages and frameworks have a similar concept; the key here is that Infusion doesn't impose a complex inheritance hierarchy or interface for your model. Java developers may recognize a similarity to the concept of POJOs (Plain Old Java Objects).
More details are at Framework Concepts#Model Objects.