docstr: Read variable value from graph collections inside of defun.
code: def testCollectionVariableValueAccess(self):
      """Read variable value from graph collections inside of defun."""
      with ops.Graph().as_default() as g:
          with self.session(graph=g):
              v = resource_variable_ops.ResourceVariable(1.0)
  
              @polymorphic_function.function
              def f():
                  return v.read_value()
  
              self.evaluate(variables.global_variables_initializer())
              self.assertEqual(1.0, float(self.evaluate(f())))
              self.assertLen(
                  ops.get_collection(ops.GraphKeys.GLOBAL_VARIABLES), 1
              )
  
file_path: tensorflow/tensorflow/python/eager/polymorphic_function/collection_test.py
imports: from tensorflow.core.protobuf import config_pb2
  from tensorflow.python.eager.polymorphic_function import polymorphic_function
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import resource_variable_ops
  from tensorflow.python.ops import variables
  from tensorflow.python.platform import test
label_desc: Use image node_id 2 for calling the FunctionCollectionTest obj's underlying member method code with example usage: obj.testCollectionVariableValueAccess() and returns: v