class_docstr: Select index of an array element from a given axis.
code: def backward(self, indexes, grad_outputs):
      return (None,)
  
imports: import numpy
  import six
  from chainer import backend
  from chainer import function_node
  import chainer.functions
  import chainer.utils
  from chainer.utils import type_check
  import chainerx
label_desc: Use image node_id 5 for calling the IndexSelectorBase obj's underlying member method code with example usage: obj.backward(indexes, grad_outputs) and returns: None