input: Write a function to sort and print out the elements of an array of integers. The function should return the sorted array.
  assert custom_sort([17, 41, 5, 22, 54, 6, 29, 3, 13])==[3, 5, 6, 13, 17, 22, 29, 41, 54]
  assert custom_sort([5, 3, 8, 6, 7, 2])==[2, 3, 5, 6, 7, 8]
  assert custom_sort([9, 1, 5])==[1, 5, 9]
  assert custom_sort([10, 20, 30])==[10, 20, 30]
  assert custom_sort([100])==[100]
output: def custom_sort(arr):
      return sorted(arr)