Reverse lexicographical using heapq

Question

Essentially I am looking for an efficient way to implement custom comparators using heapq.

For instance x = [('a',5),('c',3),('d',2),('e',1)]

I could heapify it heapq.heapify(x) then pop the min value heapq.heappop(x) which would return ('a', 5). How can I make it such that it returns in reverse lexicographical order ('e', 1)? I know the convention when it comes to numbers is simply multiply the first element of the tuple by -1. Are there simple tricks like that when it comes to strings? I know I could potentially implement a map from a to z ... z to a but it sounds cumbersome.