code: def testAttentionCellWrapperFailures(self):
      with self.assertRaisesRegexp(
          TypeError, contrib_rnn.ASSERT_LIKE_RNNCELL_ERROR_REGEXP
      ):
          contrib_rnn.AttentionCellWrapper(None, 0)
  
      num_units = 8
      for state_is_tuple in [False, True]:
          with tf.Graph().as_default():
              lstm_cell = rnn_cell.BasicLSTMCell(
                  num_units, state_is_tuple=state_is_tuple
              )
              with self.assertRaisesRegexp(
                  ValueError,
                  "attn_length should be greater than zero, got 0",
              ):
                  contrib_rnn.AttentionCellWrapper(
                      lstm_cell, 0, state_is_tuple=state_is_tuple
                  )
              with self.assertRaisesRegexp(
                  ValueError,
                  "attn_length should be greater than zero, got -1",
              ):
                  contrib_rnn.AttentionCellWrapper(
                      lstm_cell, -1, state_is_tuple=state_is_tuple
                  )
          with tf.Graph().as_default():
              lstm_cell = rnn_cell.BasicLSTMCell(
                  num_units, state_is_tuple=True
              )
              with self.assertRaisesRegexp(
                  ValueError,
                  "Cell returns tuple of states, but the flag "
                  "state_is_tuple is not set. State size is: *",
              ):
                  contrib_rnn.AttentionCellWrapper(
                      lstm_cell, 4, state_is_tuple=False
                  )
  
imports: import itertools
  from absl.testing import parameterized
  from magenta.contrib import rnn
  import numpy
  import tensorflow.compat.v1
label_desc: Use image node_id 2 for calling the RNNCellTest obj's underlying member method code with example usage: obj.testAttentionCellWrapperFailures() without return types