code: def setUp(self):
      # Skip e.g. uint64 for ChainerX.
      self._skip_chainerx_unsupported_dtype()
  
      if (
          numpy.dtype(self.in_type).kind != "f"
          or numpy.dtype(self.out_type).kind != "f"
      ):
          self.skip_backward_test = True
          self.skip_double_backward_test = True
  
      if (
          numpy.dtype(self.in_type).kind == "f"
          and self.out_type == numpy.float16
      ):
          self.check_forward_options.update(
              {"atol": 1e-3, "rtol": 1e-3}
          )
      self.check_backward_options.update(
          {"eps": 2.0**-2, "atol": 1e-2, "rtol": 1e-3}
      )
      self.check_double_backward_options.update(
          {"eps": 2.0**-2, "atol": 1e-2, "rtol": 1e-3}
      )
  
imports: import unittest
  import numpy
  import chainer
  from chainer import functions
  from chainer import testing
  from chainer.testing import attr
  import chainerx
label_desc: Use image node_id 2 for calling the TestCast obj's underlying member method code with example usage: obj.setUp() without return types