>>> import os>>> def enumfiles(path, dest):	files = os.listdir(path)	for f in files:		subpath = path + '/' + f		if (os.path.isfile(subpath)):			dest.append(subpath)		elif (os.path.isdir(subpath)):			if (f[0] == '.'):				pass			else:				enumfiles(subpath, dest)				>>> files = []>>> path = "D:/cocos2d-x-2.2.3">>> enumfiles(path, files)>>> exts = {}>>> for f in files:	l = len(f)	p = f.rfind('.')	s = f.rfind('/')	if (l>0 and p!=-1 and p>s):		ext = f[p:l]		exts[ext] = 0>>> exts.keys()