input: Write a Python function to calculate the Root Mean Squared Error (RMSE) between two NumPy arrays.
  assert rmse(np.array([1, 2, 3, 4, 5]), np.array([1.1, 2.2, 2.9, 4.1, 4.8])) == 0.14142135623730964
  assert rmse(np.array([10, 20, 30]), np.array([10, 20, 30])) == 0.0
  assert rmse(np.array([1, 3, 5]), np.array([2, 4, 6])) == 1.4142135623730951
output: def rmse(array1, array2):
      return np.sqrt(np.mean((array1 - array2) ** 2))