好用的函数，assert，random.

import random
list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
slice = random.sample(list, 5)  # 从list中随机获取5个元素，作为一个片断返回
print(slice)
print(list)# 原有序列并没有改变
[1, 8, 7, 6, 4]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

 with tf.variable_scope('model', reuse=None) as training_scope:
    print(dir(self))
    if 'weights' in dir(self):
        training_scope.reuse_variables()
        weights = self.weights
    else:
        # Define the weights
        self.weights = weights = self.construct_weights()