if values:
molSystems = set(x.molSystem for x in values)
if len(molSystems) == 1:
molSystemCode = molSystems.pop().code
if self.molSystemCode != molSystemCode:
self.molSystemCode = molSystemCode
self.symmetrySetId = None
self.chainCodes = [x.code for x in values]
else:
raise ApiError("Chains are from different MolSystems: %s" % values)
else:
self.chainCodes = ()