savedModel in tensorflow doing factorial

factorial.py

import tensorflow as tf
import os

tf.app.flags.DEFINE_string('output_dir', '/tmp/factorial_output',
                           """Directory where to export inference model.""")
tf.app.flags.DEFINE_integer('model_version', 1,
                            """Version number of the model.""")

FLAGS = tf.app.flags.FLAGS


def factorial_model(x):
    return tf.exp(tf.lgamma(x + 1))


def main(_):
    with tf.Graph().as_default():
        x = tf.placeholder(tf.float32, shape=[None])
        result = factorial_model(x)
        with tf.Session() as sess:
            output_path = os.path.join(
                tf.compat.as_bytes(FLAGS.output_dir),
                tf.compat.as_bytes(str(FLAGS.model_version)))
            print('Exporting trained model to %s' % output_path)
            builder = tf.saved_model.builder.SavedModelBuilder(output_path)

            x_info = tf.saved_model.utils.build_tensor_info(x)
            result_info = tf.saved_model.utils.build_tensor_info(result)

            classification_signature = (
                tf.saved_model.signature_def_utils.build_signature_def(
                    inputs={
                        'x':
                            x_info,
                    },
                    outputs={
                        'result':
                            result_info,
                    },
                    method_name=tf.saved_model.signature_constants.CLASSIFY_METHOD_NAME)
               )


            legacy_init_op = tf.group(
                tf.tables_initializer(), name='legacy_init_op')
            builder.add_meta_graph_and_variables(
                sess, [tf.saved_model.tag_constants.SERVING],
                signature_def_map={
                    tf.saved_model.signature_constants.
                    DEFAULT_SERVING_SIGNATURE_DEF_KEY:
                        classification_signature,
                },
                legacy_init_op=legacy_init_op)

            builder.save()
            print('Successfully exported model to %s' % FLAGS.output_dir)

if __name__ == '__main__':
    tf.app.run()