python os file operations

import os

input = open(filename, 'r')	# read
output = open(filename, 'w') # write
output = open(filename, 'a') # write more

for root, dirs, files in os.walk(path, topdown=False):
	#hanlde file
	for name in files:
		if name[:-3] = 'exe':
		print name

top='mydata/'
for root,dir,files in os.walk(top,topdown=False):
      for name in files: 
     os.remove(os.path.join(root,name))

os.rmdir('mydata')
os.mkdir('mydata')