问有没有更短的方法来导入子模块的类？

EN

import tensorflow as tf
keras = tf.contrib.keras
Sequential = keras.models.Sequential
Dense = keras.layers.Dense
Dropout = keras.layers.Dropout
Flatten = keras.layers.Flatten
Conv2D = keras.layers.Conv2D
MaxPooling2D = keras.layers.MaxPooling2D

import tensorflow as tf
keras = tf.contrib.keras
from tf.contrib.keras import (Sequential, Dense, Dropout, Flatten,
                              Conv2D, MaxPooling2D)

ImportError: No module named tf.contrib.keras

>>> from tensorflow.contrib.keras import (Sequential, Dense, Dropout, Flatten)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name Sequential

>>> import tensorflow
>>> from tensorflow.contrib.keras.models import Sequential
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named models
>>> tensorflow.contrib.keras.models.Sequential
<class 'tensorflow.contrib.keras.python.keras.models.Sequential'>