/* *******************************************************
 * Challenge exercise: Quicksort.
 * *******************************************************
 * Quicksort is another way of sorting lists, often
 * faster than insertion sort.  Quicksort starts by
 * choosing an element of the list (called a pivot);
 * we will always choose the first element.
 *
 * The list is then split into two lists: one contains
 * all elements greater than the pivot, the other contains
 * all elements less than or equal to the pivot.
 * These lists are recursively sorted (by quicksort).
 *
 * The resulting lists are sorted, and all elements in
 * one are greater than those in the other, so the two
 * lists are appended together.
 *
 * A number of helper methods are required for quicksort:
 * - Filter (greater than)
 * - Filter (less than or equal to)
 * - Append
 *
 * Design appropriate methods for your weather event list
 * classes to quicksort lists by temperature (this should
 * provide the same results as insertion sort but by
 * a different technique).
 * *******************************************************