 This often allows us to avoid storing "firstNode" and "lastNode", although if the list may be empty we need a special representation for the empty list, such as a "lastNode" variable which points to some node in the list or is "null" if it's empty; we use such a "lastNode" here.This representation significantly simplifies adding and removing nodes with a non-empty list, but empty lists are then a special case.Assuming that "someNode" is some node in a non-empty circular singly linked list, this code iterates through that list starting with "someNode"