Write a function that extracts the max value of a number in a list. If there are two or more max values, return it as a list, otherwise, return the number. This process could be relatively easy with some of the built-in list functions but the required approach is recursive.

Examples

iso_group([31, 7, 2, 13, 7, 9, 10, 13]) ➞ 31

iso_group([1, 3, 9, 5, 1, 7, 9, -9]) ➞ [9, 9]

iso_group([97, 19, -18, 97, 36, 23, -97]) ➞ [97, 97]

iso_group([-31, -7, -13, -7, -9, -13]) ➞ [-7, -7]

iso_group([-1, -3, -9, -5, -1, -7, -9, -9]) ➞ [-1, -1]

iso_group([107, 19, -18, 79, 36, 23, 97]) ➞ 107

Notes

You can read more about recursion (see the Resources tab) if you aren't familiar with it yet or haven't fully understood the concept before taking up this challenge.