input: Write a function to add corresponding elements of two arrays of the same size.
  assert add_arrays([1, 2, 3], [3, 4, 5]) == [4, 6, 8]
  assert add_arrays([10, 20, 30], [5, 15, 25]) == [15, 35, 55]
  assert add_arrays([0, 0, 0], [0, 0, 0]) == [0, 0, 0]
output: def add_arrays(arr1, arr2):
      return [x + y for x, y in zip(arr1, arr2)]