code: def _check_params(self):
      # Checks consistency of parameters
  
      if self.use_chainerx:
          assert isinstance(self.chainerx_device, str), (
              "'chainerx_device' parameter is expected to be a string "
              "representing a ChainerX device specifier"
          )
  
imports: import functools
  import chainer
  from chainer import backend
  from chainer.testing import _bundle
  from chainer.testing import attr
  import chainerx
label_desc: Use image node_id 2 for calling the BackendConfig obj's underlying member method code with example usage: obj._check_params() without return types