os (operating system)

import os

os.getcwd() # get the current directory
os.chdir() # change the current directory
os.path.join('<dir>', '<file_name>') # concatenate the strings
os.path.join(os.path.expanduser('~'), '<dir>') # expand a pathname that uses ~ to represent the current user’s home directory.
os.path.split('<dir>/<file_name>') # ('<dir>', '<file_name>') split the path and file name
('<short_name'>, '<extension>') = os.path.splitext('<file_name>') # split the file name and its extension

metadata = os.stat('<file_name>') # return an object that contains several different types of metadata about the file

metadata.st_mtime # modification time
metadata.st_size # the size of a file