Migrating TensorFlow 1 code

If the tool runs without any error, the code can be used as is. However, the tf.compat.v1 module used by the migration tool is deemed to be deprecated. Calling this module already outputs deprecation warnings, and its content will not be further updated by the community. For this reason, it is recommended that you refactor the code in order to make it more idiomatic. In the following sections, we will introduce TensorFlow 1 concepts and explain how to migrate them to TensorFlow 2. In the following examples, tf1 will be used instead of tf to denote the use of TensorFlow 1.13.