Write a function that takes a two-digit number and determines if it's the largest of two possible digit swaps.
To illustrate:
largest_swap(27) ➞ False
largest_swap(43) ➞ True
If 27 is our input, we should return False because swapping the digits gives us 72, and 72 > 27. On the other hand, swapping 43 gives us 34, and 43 > 34.
largest_swap(14) ➞ False
largest_swap(53) ➞ True
largest_swap(99) ➞ True
Numbers with two identical digits (third example) should yield True (you can't do better).