类

继承：

# Dataset 为父类
class COVID19Dataset(Dataset):
    pass

构造方法：__init__(self)
长度：__len__
取值：__getitem__

文件

打开文件：with open 可以自动关闭

# 写文件
with open("test.txt", "wt") as out_file:
    out_file.write("该文本会写入到文件中\n看到我了吧！")
# Read a file
with open("test.txt", "rt") as in_file:
    text = in_file.read()
print(text)