code: def testSimple(self):
      with ops.Graph().as_default() as g:
          with ops.device("/cpu:0"):
              x = array_ops.placeholder(dtypes.float32)
              pi = array_ops.placeholder(dtypes.int64)
              gi = array_ops.placeholder(dtypes.int64)
              v = 2.0 * (array_ops.zeros([128, 128]) + x)
          with ops.device(test.gpu_device_name()):
              stager = data_flow_ops.MapStagingArea([dtypes.float32])
              stage = stager.put(pi, [v], [0])
              k, y = stager.get(gi)
              y = math_ops.reduce_max(math_ops.matmul(y, y))
  
      g.finalize()
  
      with self.session(graph=g) as sess:
          sess.run(stage, feed_dict={x: -1, pi: 0})
          for i in range(10):
              _, yval = sess.run(
                  [stage, y], feed_dict={x: i, pi: i + 1, gi: i}
              )
              self.assertAllClose(
                  4 * (i - 1) * (i - 1) * 128, yval, rtol=1e-4
              )
  
imports: import queue
  import threading
  import numpy
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import data_flow_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 1 for calling the MapStageTest obj's underlying member method code with example usage: obj.testSimple() without return types