code: def _test_three_recurrent_children(self, gpu):
      # Test if https://github.com/chainer/chainer/issues/6053 is addressed
      in_size = 2
      out_size = 6
  
      rseq = StatelessRecurrentSequential(
          L.NStepLSTM(1, in_size, 3, 0),
          L.NStepGRU(2, 3, 4, 0),
          L.NStepRNNTanh(5, 4, out_size, 0),
      )
  
      if gpu >= 0:
          chainer.cuda.get_device_from_id(gpu).use()
          rseq.to_gpu()
      xp = rseq.xp
  
      seqs_x = [
          xp.random.uniform(-1, 1, size=(4, in_size)).astype(
              np.float32
          ),
          xp.random.uniform(-1, 1, size=(1, in_size)).astype(
              np.float32
          ),
          xp.random.uniform(-1, 1, size=(3, in_size)).astype(
              np.float32
          ),
      ]
  
      # Make and load a recurrent state to check if the order is correct.
      _, rs = rseq.n_step_forward(seqs_x, None, output_mode="concat")
      _, _ = rseq.n_step_forward(seqs_x, rs, output_mode="concat")
  
      _, rs = rseq.n_step_forward(seqs_x, None, output_mode="split")
      _, _ = rseq.n_step_forward(seqs_x, rs, output_mode="split")
  
imports: import unittest
  import chainer
  from chainer import functions
  from chainer import links
  from chainer import testing
  import numpy
  from chainerrl.links import StatelessRecurrentSequential
label_desc: Use image node_id 13 for calling the TestStatelessRecurrentSequential obj's underlying member method code with example usage: obj._test_three_recurrent_children(gpu) without return types