Feature(description: String, extractor: (T) -> R)
Parameter object which contains a description of a feature along with an extractor which actually extracts the feature out of a subject of an assertion.
Use of(K..., ...) { ... } to create this representation where the first argument is the extractor in form of a
KProperty1 or a KFunctionX and the remaining arguments are the required arguments in case of a KFunctionX
where X > 1.