tf_group_doesnt_return.py

import numpy as np
import tensorflow as tf
from tensorflow.python.ops.data_flow_ops import StagingArea

dataset_range = tf.contrib.data.Dataset.range(10)
iter = dataset_range.make_one_shot_iterator()
next_item = iter.get_next()

area = StagingArea(dtypes=[tf.int64])
area_put = area.put([next_item])
area_get = area.get()

with tf.Session() as sess:
    print('put:', sess.run(area_put))
    print('size:', sess.run(area.size()))
    print('put(); get() =', sess.run(tf.group(area_put, area_get)))
    print('size:', sess.run(area.size()))

# put: None
# size: 1
# put(); get() = None
# size: 1