Assertion: interface's method | /r/CapableOf | throw exception
Facets:
Source sentences:
text: The methods pollFirst and pollLast return null if the Deque is empty whereas the methods removeFirst and removeLast throw an exception if the Deque instance is empty.
text: The methods getFirst and getLast throw an exception if the deque instance is empty whereas the methods peekFirst and peekLast return NULL .