reason ：
Check the code carefully , The reason is that the file to be created The directory does not exist .
namely ： To create a /a/b/c/d.txt, You need to guarantee /a/b/c Directory exists .
The code first detects whether the directory exists , If it does not exist, create a multi-level directory first ：
if not os.path.exists(prefix_dir):
os.makedirs(prefix_dir)attach ：
Create multi-level directory ：os.makedirs()
Create directory ：os.mkdir()
create a file ：os.mknod()
