code: def backward(self, dZ):
      ctx = context(dZ)
      X, Y = self.saved_tensors
      gidx, op = self.gidx, self.op
      lhs_target, rhs_target = self.lhs_target, self.rhs_target
      if op != "copy_rhs":
          if lhs_target in ["u", "v"]:
              _gidx = gidx if self.lhs_target == "v" else gidx.reverse()
              if op in ["add", "sub", "copy_lhs"]:
                  dX = _gspmm(_gidx, "copy_rhs", "sum", None, dZ)[0]
              else:  # mul, div, dot
                  if rhs_target == lhs_target:
                      dX = _gspmm(_gidx, "copy_rhs", "sum", None, dZ)[
                          0
                      ] * _muldiv(op, Y)
                  elif self.rhs_target == "e":
                      dX = _gspmm(
                          _gidx,
                          "copy_rhs",
                          "sum",
                          None,
                          dZ * _muldiv(op, Y),
                      )[0]
                  else:  # rhs_target = !lhs_target
                      dX = _gspmm(
                          _gidx, "mul", "sum", _muldiv(op, Y), dZ
                      )[0]
          else:  # lhs_target == 'e'
              if op in ["add", "sub", "copy_lhs"]:
                  dX = dZ
              else:  # mul, div, dot
                  dX = _gsddmm(
                      gidx, "mul", dZ, _muldiv(op, Y), "e", rhs_target
                  )
          dX = _reduce_grad(dX, X.shape)
      else:
          dX = nd.zeros_like(X)
      if op != "copy_lhs":
          if self.rhs_target in ["u", "v"]:
              _gidx = gidx if rhs_target == "v" else gidx.reverse()
              if op in ["add", "sub", "copy_rhs"]:
                  dY = _gspmm(
                      _gidx, "copy_rhs", "sum", None, _addsub(op, dZ)
                  )[0]
              else:  # mul, div, dot
                  if lhs_target == rhs_target:
                      dY = (
                          _gspmm(_gidx, "copy_rhs", "sum", None, dZ)[0]
                          * X
                      )
                  elif self.lhs_target == "e":
                      dY = _gspmm(
                          _gidx, "copy_rhs", "sum", None, dZ * X
                      )[0]
                  else:  # rhs_target = !lhs_target
                      dY = _gspmm(_gidx, "mul", "sum", X, dZ)[0]
                  if op == "div":
                      dY = -dY / (Y**2)
          else:
              if op in ["add", "sub", "copy_rhs"]:
                  dY = _addsub(op, dZ)
              else:  # mul, div, dot
                  dY = _gsddmm(gidx, "mul", dZ, X, "e", lhs_target)
                  if op == "div":
                      dY = -dY / (Y**2)
          dY = _reduce_grad(dY, Y.shape)
      else:
          dY = nd.zeros_like(Y)
      self.saved_tensors = None
      return dX, dY
  
imports: import mxnet
  import numpy
  from mxnet import nd
  from ..._sparse_ops import _bwd_segment_cmp, _csrmask, _csrmm, _csrsum, _gsddmm, _gspmm, _scatter_add, _segment_reduce
  from ...base import ALL, dgl_warning, is_all
  from ...heterograph_index import create_unitgraph_from_csr
  from .tensor import asnumpy, context, copy_to, to_backend_ctx, zerocopy_from_numpy
label_desc: Use image node_id 3 for calling the GSDDMM obj's underlying member method code with example usage: obj.backward(dZ) and returns: dX,  dY