fun <E : Any, T : Iterable<E?>> Expect<T>.all(assertionCreatorOrNull: (Expect<E>.() -> Unit)?): Expect<T>
Expects that the subject of the assertion (an Iterable) has at least one element and
that either every element holds all assertions created by the assertionCreatorOrNull or
that all elements are null in case assertionCreatorOrNull is defined as null.
AssertionError - Might throw an AssertionError if the assertion made is not correct.
Return
An Expect for the current subject of the assertion.