Python多个上下文管理器
示例
您可以同时打开多个内容管理器：
with open(input_path) as input_file, open(output_path, 'w') as output_file:
#对两个文件都做一些事情。
#例如，将input_file的内容复制到output_file
for line in input_file:
output_file.write(line + '\n')它与嵌套上下文管理器具有相同的效果：
with open(input_path) as input_file:
with open(output_path, 'w') as output_file:
for line in input_file:
output_file.write(line + '\n')