code: def test_rmse_two():
      rmse = pm.rmse([1, 2], [1, 2])
      assert isinstance(rmse, float)
      assert rmse == approx(0)
  
      rmse = pm.rmse([1, 1], [2, 2])
      assert rmse == approx(1)
  
      rmse = pm.rmse([1, 3], [3, 1])
      assert rmse == approx(2)
  
      rmse = pm.rmse([1, 3], [3, 2])
      assert rmse == approx(np.sqrt(5 / 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 8 for calling a global function with example usage: test_rmse_two() without return types