Find All Numbers Disappeared in an Array : leetcode solution in python

class Solution:
    def findDisappearedNumbers(self, nums: List[int]) -> List[int]:
        try:
            length_nums = len(nums)
            all_numbers_set = set(range(1, length_nums + 1))

            for num in nums:
                if num in all_numbers_set:
                    all_numbers_set.remove(num)

            return list(all_numbers_set)



        except:
            pass