Python code that implements the quicksort algorithm

This code sorts an array of integers in ascending order using the quicksort algorithm. The basic idea of quicksort is to pick a "pivot" element from the array, partition the other elements into two sub-arrays, those less than and those greater than the pivot, and then recursively sort the sub-arrays. The pivot is selected as the middle element of the array, but in practice it can be any element.

In this example, the input array is [3, 6, 8, 10, 1, 2, 1] and the output is [1, 1, 2, 3, 6, 8, 10].