code: def setup(self, float_dtype):
      dtype = float_dtype
  
      if dtype == "float16":
          self.check_forward_options.update(
              {"rtol": 1e-3, "atol": 1e-3}
          )
          self.check_backward_options.update(
              {"rtol": 5e-2, "atol": 5e-2}
          )
          self.check_double_backward_options.update(
              {"rtol": 5e-2, "atol": 5e-2}
          )
  
      self.dtype = dtype
  
imports: import chainer
  import chainerx
  import numpy
  from chainerx_tests import math_utils
  from chainerx_tests import op_utils
label_desc: Use image node_id 1 for calling the TestErf obj's underlying member method code with example usage: obj.setup(float_dtype) without return types