code: def test_rmse():
      """Tests for the RMSE function."""
  
      predictions = [pred(0, 0), pred(1, 1), pred(2, 2), pred(100, 100)]
      assert rmse(predictions) == 0
  
      predictions = [pred(0, 0), pred(0, 2)]
      assert rmse(predictions) == sqrt((0 - 2) ** 2 / 2)
  
      predictions = [pred(2, 0), pred(3, 4)]
      assert rmse(predictions) == sqrt(
          ((2 - 0) ** 2 + (3 - 4) ** 2) / 2
      )
  
      with pytest.raises(ValueError):
          rmse([])
  
imports: from math import sqrt
  import pytest
  from surprise.accuracy import fcp, mae, mse, rmse
label_desc: Use image node_id 3 for calling a global function with example usage: test_rmse() without return types