code: def test_reducer():
      x = torch.randn(5, 5)
      r = torchdrift.reducers.Reducer()
      with pytest.raises(NotImplementedError):
          r.fit(x)
      with pytest.raises(NotImplementedError):
          r(x)
  
imports: import pytest
  import torchdrift
  import torch
  import sklearn.decomposition
label_desc: Use image node_id 3 for calling a global function with example usage: test_reducer() without return types