code: def test_rmse_array_two():
      rmse = pm.rmse(np.array([1, 2]), np.array([1, 2]))
      assert isinstance(rmse, float)
      assert rmse == approx(0)
  
      rmse = pm.rmse(np.array([1, 1]), np.array([2, 2]))
      assert rmse == approx(1)
  
      rmse = pm.rmse(np.array([1, 3]), np.array([3, 1]))
      assert rmse == approx(2)
  
imports: import numpy
  import pandas
  import os.path
  from pytest import approx, raises, mark, skip
  import lenskit.metrics.predict
  import lenskit.util.test
label_desc: Use image node_id 9 for calling a global function with example usage: test_rmse_array_two() without return types