区别于默认初始化，自定义初始化

# 内置初始化
def init_normal(m):     # m is net
    if type(m) == nn.Linear():
        # "_" is replace, is not return
        nn.init.normal_(m.weight, mean=0. std=0.01) # 正态分布
        # nn.init.constant_(m.weight, 1)
        nn.init.zeros_(m.bias)      # 置零

net.apply(init_normal)   # 对网络进行遍历，遍历执行init_normal
net[0].weight.data[0]
net[0].bias.data[0]