code: def forward_expected(self, inputs):
      (x,) = inputs
      y = numpy.log(1 + numpy.exp(self.beta * x)) / self.beta
      return (utils.force_array(y).astype(self.dtype),)
  
file_path: chainer/tests/chainer_tests/functions_tests/activation_tests/test_softplus.py
imports: import numpy
  from chainer import functions
  from chainer import testing
  from chainer import utils
label_desc: Use image node_id 3 for calling the TestSoftplus obj's underlying member method code with example usage: obj.forward_expected(inputs) and returns: utils