/**
* Returns and removes the first element, ie. that one with the highest priority, from the queue.
* @param q The priority queue.
* @return The first element of the queue. Asserts if queue is empty.
*/
/**
* Returns and removes the first element, ie. that one with the highest priority, from the queue.
* @param q The priority queue.
* @return The first element of the queue. Asserts if queue is empty.
*/