code: def test_scan(self):
      # Test the compute_test_value mechanism Scan.
  
      orig_compute_test_value = theano.config.compute_test_value
      try:
          theano.config.compute_test_value = "raise"
          # theano.config.compute_test_value = 'warn'
          k = T.iscalar("k")
          A = T.vector("A")
          k.tag.test_value = 3
          A.tag.test_value = np.random.rand(5).astype(config.floatX)
  
          def fx(prior_result, A):
              return prior_result * A
  
          # Symbolic description of the result
          result, updates = theano.scan(
              fn=fx,
              outputs_info=T.ones_like(A),
              non_sequences=A,
              n_steps=k,
          )
  
          # We only care about A**k, but scan has provided us with A**1 through A**k.
          # Discard the values that we don't care about. Scan is smart enough to
          # notice this and not waste memory saving them.
          final_result = result[-1]
          assert hasattr(final_result.tag, "test_value")
      finally:
          theano.config.compute_test_value = orig_compute_test_value
  
imports: from __future__ import absolute_import, print_function, division
  import os
  import sys
  import traceback
  import warnings
  import numpy
  from nose.plugins.skip import SkipTest
  import unittest
  import theano
  from theano import config
  from theano import scalar
  from theano import tensor
  from theano.gof import Apply, Op
  from theano.gof import utils
  from theano.tensor.basic import _allclose
label_desc: Use image node_id 10 for calling the TestComputeTestValue obj's underlying member method code with example usage: obj.test_scan() and returns: unknown