The Session graph is empty.Add operations to the graph before calling run()

1.我的环境是 Python3.6，tensorflow的版本是1.13.1。
如果不加tf.compat.v1.enable_v2_behavior()这句代码的话程序是可以正常运行的。
但是加上的话就报错：RuntimeError: The Session graph is empty.Add operations to the graph before calling run().
我需要加上tf.compat.v1.enable_v2_behavior()这句代码也需要运行sess，请问怎么修改代码？

import numpy as np
import tensorflow as tf
tf.compat.v1.enable_v2_behavior()
if __name__=='__main__':
    sess = tf.Session()
    a = tf.Variable(1)
    sess.run(tf.global_variables_initializer())
    b = []
    b += [a]
    c = 2
    sess.run(b[0].assign(c))
    sess.close()

你好，你可以试一下

import numpy as np
import tensorflow as tf

sess = tf.compat.v1.Session()
with tf.compat.v1.get_default_graph().as_default():

    a = tf.Variable(1)
    sess.run(tf.compat.v1.global_variables_initializer())
    b = []
    b += [a]
    c = 2
    sess.run(b[0].assign(c))
    print(sess.run(b))
    sess.close()