docstr: copied from test_chain_structure
docstr_tok: ["copied","from","test_chain_structure"]
code: def test_scan(self):
      """copied from test_chain_structure"""
  
      def cumsum(x):
          return tf.scan(lambda a, x: a + x, x)
  
      with self.test_session():
          a = Normal(tf.ones([3]), tf.ones([3]))
          b = Normal(cumsum(a), tf.ones([3]))
          c = Normal(cumsum(b), tf.ones([3]))
          d = Normal(cumsum(c), tf.ones([3]))
          e = Normal(cumsum(d), tf.ones([3]))
          self.assertEqual(get_parents(a), [])
          self.assertEqual(get_parents(b), [a])
          self.assertEqual(get_parents(c), [b])
          self.assertEqual(get_parents(d), [c])
          self.assertEqual(get_parents(e), [d])
  
file_path: edward/tests/util/get_parents_test.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import tensorflow
  from edward.models import Bernoulli, Normal
  from edward.util import get_parents
label_desc: Use image node_id 6 for calling the test_get_parents_class obj's underlying member method code with example usage: obj.test_scan() and returns: tf