code: def forward_cpu(self, x):
      self.retain_inputs((0,))
      return (utils.force_array(numpy.log1p(x[0])),)
  
file_path: chainer/chainer/functions/math/logarithm_1p.py
imports: import numpy
  from chainer.backends import cuda
  from chainer import function_node
  from chainer import utils
  from chainer.utils import type_check
label_desc: Use image node_id 3 for calling the Log1p obj's underlying member method code with example usage: obj.forward_cpu(x) and returns: utils