input: Write a function to swap the elements of two arrays of integers. The function should take two arrays as input and swap each corresponding element between the two arrays. Both arrays will always be of the same length.
  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([1], [2])==([2], [1])
  assert swap([], [])==([], [])
output: def swap(arr1, arr2):
      for i in range(len(arr1)):
          arr1[i], arr2[i] = arr2[i], arr1[i]
      return arr1, arr2