Design a queue data structure that prioritizes the most recently used element. The queue must efficiently move the accessed element to the end while maintaining other elements' relative order.

You are given a 2D matrix and need to sort the elements along each diagonal. Rearrange the matrix so that elements on the same diagonal are in non-decreasing order.

You're given a string that represents a JSON object. Your task is to parse this string and convert it into a usable object or data structure within your programming language.