text: import tensorflow as tf
  
  '''
  pipenv --pypi-mirror https://mirrors.aliyun.com/pypi/simple/ install -v tensorflow-gpu
  reference: 
      https://pipenv.readthedocs.io/en/latest/#cmdoption-pipenv-install-extra-index-url
  '''
  
  # np.dot(m1,m2)
  # with tf.device('/device:GPU:0'):
  #     product = tf.matmul(matrix1, matrix2)
  
  # Creates a graph.
  a = tf.constant([1.0, 2.0, 3.0, 4.0, 5.0, 6.0], shape=[2, 3], name='a')
  b = tf.constant([1.0, 2.0, 3.0, 4.0, 5.0, 6.0], shape=[3, 2], name='b')
  c = tf.matmul(a, b)
  # Creates a session with log_device_placement set to True.
  sess = tf.Session(config=tf.ConfigProto(log_device_placement=True))
  # Runs the op.
  print(sess.run(c))
  