input: Write a python function to sort an array and modify the arrangement by interleaving each element with itself.
  assert modifiedArrangement([1, 4, 5, 2, 9, 0]) == [0, 0, 1, 1, 2, 2, 4, 4, 5, 5, 9, 9]
  assert modifiedArrangement([3, 1, 2]) == [1, 1, 2, 2, 3, 3]
  assert modifiedArrangement([10, 5, 3, 8]) == [3, 3, 5, 5, 8, 8, 10, 10]
output: def modifiedArrangement(arr):
      arr.sort()
      result = []
      for num in arr:
          result.extend([num, num])
      return result