class_docstr: Concatenate variables along a new axis.
class_docstr_tok: ["Concatenate","variables","along","a","new","axis","."]
code: def backward(self, inputs, grads):
      return chainer.functions.separate(grads[0], self.axis)
  
file_path: chainer/chainer/functions/array/stack.py
imports: import chainer
  from chainer import backend
  from chainer import function_node
  from chainer.utils import type_check
  import chainerx
label_desc: Use image node_id 5 for calling the Stack obj's underlying member method code with example usage: obj.backward(inputs, grads) and returns: chainer