code: def setUp(self):
      self.link = RPN(scales=(1 / 2, 1 / 4, 1 / 8))
  
imports: from __future__ import division
  import numpy
  import unittest
  import chainer
  from chainer import testing
  from chainer.testing import attr
  from chainercv.links.model.fpn import RPN
  from chainercv.links.model.fpn import rpn_loss
label_desc: Use image node_id 1 for calling the TestRPN obj's underlying member method code with example usage: obj.setUp() without return types