tf.estimator.Estimator：
https://www.cnblogs.com/wushangjue/p/8334539.html
https://www.cnblogs.com/zongfa/p/10149483.html
https://zhuanlan.zhihu.com/p/74857888
tf.estimator.train_and_evaluate：
https://blog.csdn.net/u014061630/article/details/83109642
待 https://blog.csdn.net/u014061630/article/details/83109642
https://tensorflow.juejin.im/get_started/custom_estimators.html
https://www.cnblogs.com/marsggbo/p/11232897.html