class_docstr: Sum of array elements over a given axis.
code: def forward(self, inputs):
      (x,) = inputs
      ret = x.sum(axis=self.axis, keepdims=self.keepdims)
      if backend.get_array_module(x) is numpy:
          ret = numpy.asarray(ret)
      return (ret,)
  
imports: import numpy
  import six
  import chainer
  from chainer import backend
  from chainer import function_node
  from chainer import utils
  from chainer.utils import type_check
  import chainerx
label_desc: Use image node_id 4 for calling the Sum obj's underlying member method code with example usage: obj.forward(inputs) and returns: ret