- int index
indexth element, or
null if there is no such element.
Returns the element at position
index of this iterable,
just like elementAt, if this iterable has such an element.
If this iterable does not have enough elements to have one with the given
null value is returned, unlike elementAt which throws
index must not be negative.
T? elementAtOrNull(int index) => skip(index).firstOrNull;