code: def test_addhook_returns_self(self):
      model, x, dot = self._create_model_and_data()
      hook = MyLinkHook()
      ret = model.add_hook(hook)
      assert ret is model
  
imports: import time
  import unittest
  import numpy
  import chainer
  from chainer import testing
label_desc: Use image node_id 7 for calling the TestLinkHook obj's underlying member method code with example usage: obj.test_addhook_returns_self() without return types