code: def backward(self, inputs, grads):
      xp = backend.get_array_module(*inputs)
  
      c_prev1, c_prev2, x1, x2, c, gc, gh = inputs
      ggc_prev1, ggc_prev2, ggx1, ggx2 = grads
  
      gc_is_none = gc is None
      gh_is_none = gh is None
      if gc_is_none:
          gc = 0
      if gh_is_none:
          gh = 0
      if ggc_prev1 is None:
          ggc_prev1 = 0
      if ggc_prev2 is None:
          ggc_prev2 = 0
  
      gc_prev1 = xp.empty_like(c_prev1)
      gc_prev2 = xp.empty_like(c_prev2)
      gx1 = xp.empty_like(x1)
      gx2 = xp.empty_like(x2)
      gc_next = xp.empty_like(c)
      ggc = xp.empty_like(c_prev1)
      ggh = xp.empty_like(c)
  
      a1, i1, f1, o1 = _extract_gates(x1)
      a2, i2, f2, o2 = _extract_gates(x2)
      gga1, ggi1, ggf1, ggo1 = _extract_gates(ggx1)
      gga2, ggi2, ggf2, ggo2 = _extract_gates(ggx2)
      ga1, gi1, gf1, go1 = _extract_gates(gx1)
      ga2, gi2, gf2, go2 = _extract_gates(gx2)
  
      o = o1 + o2
  
      (
          gc_prev1[:],
          ga1[:],
          gi1[:],
          gf1[:],
          go1[:],
          gc_prev2[:],
          ga2[:],
          gi2[:],
          gf2[:],
          go2[:],
          gc_next[:],
          ggc[:],
          ggh[:],
      ) = slstm_grad_grad(
          c_prev1,
          a1,
          i1,
          f1,
          c_prev2,
          a2,
          i2,
          f2,
          o,
          c,
          gc,
          gh,
          ggc_prev1,
          gga1,
          ggi1,
          ggf1,
          ggo1,
          ggc_prev2,
          gga2,
          ggi2,
          ggf2,
          ggo2,
      )
  
      # If inputs were omitted, omit their gradients.
      if gc_is_none:
          ggc = None
      if gh_is_none:
          ggh = None
  
      return gc_prev1, gc_prev2, gx1, gx2, gc_next, ggc, ggh
  
imports: import numpy
  import six
  from chainer import backend
  from chainer.backends import cuda
  from chainer.backends import intel64
  from chainer import function
  from chainer import function_node
  from chainer.utils import type_check
  import chainerx
label_desc: Use image node_id 2 for calling the SLSTMGrad obj's underlying member method code with example usage: obj.backward(inputs, grads) and returns: gc_prev1,  gc_prev2,  gx1,  gx2,  gc_next,  ggc,  ggh