code: def forward_gpu(self, x):
      self.retain_outputs((0,))
      return (
          cuda.elementwise(
              "T x",
              "T y",
              "y = erfcinv(x)",
              "elementwise_erfcinv",
          )(x[0]),
      )
  
file_path: chainer/chainer/functions/math/erfcinv.py
imports: import math
  import chainer
  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 4 for calling the ErfcInv obj's underlying member method code with example usage: obj.forward_gpu(x) and returns: cuda