code: def test_prepare_original_unaffected(self):
      original = np.random.uniform(size=(self.in_channels, 286, 286))
      input_ = original.copy()
      self.link._prepare(input_)
      np.testing.assert_equal(original, input_)
  
imports: import numpy
  import unittest
  import chainer
  from chainer import testing
  from chainer.testing import attr
  from chainercv.links import FeaturePredictor
label_desc: Use image node_id 3 for calling the TestFeaturePredictor obj's underlying member method code with example usage: obj.test_prepare_original_unaffected() without return types