input: Write a python function to find the two elements in an array whose sum is closest to zero.
  assert find_closest_sum_of_two([1, -1, 2, -2, 3, -3]) == (1, -1, 0)
  assert find_closest_sum_of_two([10, 22, 28, 29, 30, 40]) == (28, 29, 57)
  assert find_closest_sum_of_two([1, 60, -10, 70, -80, 85]) == (-80, 85, 5)
  assert find_closest_sum_of_two([5, 8, -3, 2, -7, -10]) == (5, -3, 2)
output: def find_closest_sum_of_two(arr):
      arr.sort()
      left = 0
      right = len(arr) - 1
      closest_sum = float('inf')
      closest_pair = (0, 0)
      
      while left < right:
          current_sum = arr[left] + arr[right]
          
          if abs(current_sum) < abs(closest_sum):
              closest_sum = current_sum
              closest_pair = (arr[left], arr[right])
          
          if current_sum < 0:
              left += 1
          else:
              right -= 1
      
      return closest_pair + (closest_sum,)