code: def test_chain_operator_three(model1, model2, model3):
      # Previously we 'flattened' these nested calls. We might opt to do so
      # again, especially for the operators.
      with Model.define_operators({">>": chain}):
          model = model1 >> model2 >> model3
          assert len(model.layers) == 2
          assert len(model.layers[0].layers) == 2
  
imports: import numpy
  import pytest
  from numpy.testing import assert_allclose
  from thinc.api import Dropout, Linear, Model, NumpyOps, add, clone, concatenate, map_list, noop
  from thinc.layers import chain, tuplify
label_desc: Use image node_id 21 for calling a global function with example usage: test_chain_operator_three(model1, model2, model3) without return types