code: def forward_expected(self, inputs):
      (x,) = inputs
      return (x.astype(self.out_type),)
  
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 4 for calling the TestCast obj's underlying member method code with example usage: obj.forward_expected(inputs) and returns: x