code: def test_rmse_one():
      rmse = pm.rmse([1], [1])
      assert isinstance(rmse, float)
      assert rmse == approx(0)
  
      rmse = pm.rmse([1], [2])
      assert rmse == approx(1)
  
      rmse = pm.rmse([1], [0.5])
      assert rmse == approx(0.5)
  
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 7 for calling a global function with example usage: test_rmse_one() without return types