Return the minimum age of a set of files.
	Returns 0 if no paths are given.
	Returns time.time() if a path does not exist.

def age(*paths):
	'''Return the minimum age of a set of files.
	Returns 0 if no paths are given.
	Returns time.time() if a path does not exist.'''
	if not paths:
		return 0

	for path in paths:
		if not os.path.exists(path):
			return time.time()

	return min([(time.time() - os.path.getmtime(path)) for path in paths])