code: def test_original_unaffected_by_setting_pick(self):
      with self.check_unchanged(self.original_link, self.x):
          self.link.pick = "f2"
  
imports: import numpy
  import unittest
  import chainer
  from chainer.backends.cuda import to_cpu
  from chainer.function import Function
  from chainer import testing
  from chainer.testing import attr
  from chainercv.links import PickableSequentialChain
  from chainercv.utils.testing import ConstantStubLink
label_desc: Use image node_id 3 for calling the TestCopiedPickableSequentialChain obj's underlying member method code with example usage: obj.test_original_unaffected_by_setting_pick() without return types