code: def __call__(self, xs, ts):
      h1 = [self.l1(x) for x in xs]
      # MultiNodeNStepRNN returns outputs of actual_rnn + delegate_variable.
      cell1, cell2, os, delegate_variable = self.rnn(h1)
      os = F.concat(os, axis=0)
      h2 = self.l2(os)
      h3 = self.l3(h2)
      ys = F.sum(h3, axis=0)
      err = F.mean_squared_error(ys, ts)
      (err,) = chainermn.functions.pseudo_connect(
          delegate_variable, err
      )
      return err
  
imports: import chainer
  import chainer.backends
  from chainer.backends.cuda import cupy
  import chainer.functions
  import chainer.links
  import chainer.testing
  import chainer.testing.attr
  import chainermn
  import numpy
  import pytest
label_desc: Use image node_id 2 for calling the Model obj's underlying member method code with example usage: obj.__call__(xs, ts) and returns: err