molSystem = self.root.findFirstMolSystem(code=self.molSystemCode)
if molSystem:
chainCodes = self.chainCodes
if chainCodes:
result = tuple(molSystem.findFirstChain(code=x) for x in chainCodes)
if None in result:
result = tuple()
else:
result = tuple(molSystem.sortedChains())
else:
result = tuple()