Implement a generic KeyValuePair class, where the Key is generic and the Value is also generic but is restricted to numeric data types.

Given a queue with O(1) methods add, remove, and size, what is the big-Oh efficiency of moving the element at the head of the queue to the tail? Of moving the element at the tail of the queue to the head? (The order of the other queue elements should be unchanged.)

R16.10 It is not safe to remove the first element of a linked list with the removeFirst method when an iterator has just traversed the first element. Explain the problem by tracing the code and drawing a diagram.