code: def backward(self, indexes, grad_outputs):
      x, divisor = self.get_retained_inputs()
      (gw,) = grad_outputs
      return gw, -chainer.functions.fix(x / divisor) * gw
  
file_path: chainer/chainer/functions/math/fmod.py
imports: from chainer import backend
  from chainer import function_node
  import chainer.functions
  from chainer import utils
  from chainer.utils import type_check
label_desc: Use image node_id 4 for calling the Fmod obj's underlying member method code with example usage: obj.backward(indexes, grad_outputs) and returns: gw,  unknown