input: Write a python function to find the kth smallest element in an array.
  assert find_kth_smallest([7, 10, 4, 3, 20, 15], 3) == 7
  assert find_kth_smallest([7, 10, 4, 3, 20, 15], 4) == 10
  assert find_kth_smallest([7, 10, 4, 3, 20, 15], 1) == 3
output: def find_kth_smallest(arr, k):
      arr.sort()
      return arr[k-1]