code: def setUp(self):
      if self.dtype == numpy.float16:
          self.check_forward_dtype = numpy.float32
          self.check_forward_options.update(
              {"atol": 1e-3, "rtol": 1e-3}
          )
          self.check_backward_options.update(
              {"atol": 1e-3, "rtol": 1e-3}
          )
          self.check_double_backward_options.update(
              {"atol": 5e-3, "rtol": 5e-3}
          )
      else:
          self.check_forward_dtype = self.dtype
          self.check_forward_options.update(
              {"atol": 1e-4, "rtol": 1e-4}
          )
          self.check_backward_options.update(
              {"atol": 5e-4, "rtol": 5e-4}
          )
          self.check_double_backward_options.update(
              {"atol": 5e-4, "rtol": 5e-4}
          )
  
imports: import unittest
  import numpy
  import chainer
  from chainer.backends import cuda
  from chainer import functions
  from chainer import testing
  from chainer.testing import attr
  from chainer.utils import type_check
label_desc: Use image node_id 1 for calling the InvFunctionTest obj's underlying member method code with example usage: obj.setUp() without return types