input: Write a function to swap elements between two arrays of integers of the same length. Return the modified arrays.
  def swap(arr1, arr2):
      assert len(arr1) == len(arr2)
      for i in range(len(arr1)):
          temp = arr1[i]
          arr1[i] = arr2[i]
          arr2[i] = temp
  
  assert swap([3, 5, 6, 9], [2, 4, 7, 8])==([2, 4, 7, 8], [3, 5, 6, 9])
  assert swap([1, 2, 3], [4, 5, 6])==([4, 5, 6], [1, 2, 3])
  assert swap([10, 20], [30, 40])==([30, 40], [10, 20])
  assert swap([7], [8])==([8], [7])
  assert swap([], [])==([], [])
  assert swap([5, 4, 3, 2, 1], [1, 2, 3, 4, 5])==([1, 2, 3, 4, 5], [5, 4, 3, 2, 1])
output: def swap(arr1, arr2):
      for i in range(len(arr1)):
          arr1[i], arr2[i] = arr2[i], arr1[i]
      return arr1, arr2