def _fanMatch(fan, uFan, dWings):
	""" Twist a single fan so it matches the uFan if it can """
	uIdx = uFan[0]
	for f, fIdx in enumerate(fan):
		dw = dWings.get(fIdx, [])
		if uIdx in dw:
			return fan[f:] + fan[:f]
	return None