有沒(méi)有辦法解決字典理解問(wèn)題？bmcdsreg = {}for key, val in bms.iteritems():    bmcdsreg[key] = {}    for reg in bmmaps.columns:        bmcdsreg[key][reg]= val*bmmaps[reg]我有以下密鑰互換的版本：bmcdsreg = {reg: {key: val*bmmaps[reg] for key, val in bms.iteritems()}             for reg in bmmaps.columns}