code: def _sum(dx, x):
      axes = [a for a in range(x.ndim - 2) if dx.shape[a] != x.shape[a]]
      dx = F.sum(dx, axes, keepdims=True) if axes != [] else dx
      return dx
  
label_desc: Use image node_id 1 for calling a global function with example usage: _sum(dx, x) and returns: dx