code: def test_scan(self):
      # Test the compute_test_value mechanism Scan.
      k = iscalar("k")
      A = vector("A")
      k.tag.test_value = 3
      A.tag.test_value = np.random.random((5,)).astype(config.floatX)
  
      def fx(prior_result, A):
          return prior_result * A
  
      # Symbolic description of the result
      result, updates = pytensor.scan(
          fn=fx,
          outputs_info=pt.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")
  
imports: import numpy
  import pytest
  import pytensor
  import pytensor.tensor
  from pytensor import scalar
  from pytensor.configdefaults import config
  from pytensor.graph import utils
  from pytensor.graph.basic import Apply
  from pytensor.graph.op import Op
  from pytensor.graph.type import Type
  from pytensor.link.c.op import COp
  from pytensor.tensor.math import _allclose, dot
  from pytensor.tensor.type import fmatrix, iscalar, matrix, vector
label_desc: Use image node_id 11 for calling the TestComputeTestValue obj's underlying member method code with example usage: obj.test_scan() and returns: unknown