Duck typing, must it be dynamic?

Question

Wikipedia used to say* about duck-typing:

In computer programming with object-oriented programming languages, duck typing is a style of dynamic

Answer 1

There are always going to be examples from some programming languages that violate some definitions of various terms. For example, ActionScript supports doing duck-typing style programming on instances that are not technically dynamic.

var x:Object = new SomeClass();
if ("begin" in x) {
    x.begin();
}

In this case we tested if the object instance in "x" has a method "begin" before calling it instead of using an interface. This works in ActionScript and is pretty much duck-typing, even though the class SomeClass() may not itself be dynamic.