code: def GetTZInfo(tzname='UTC', utcOffset=None, dst=None):
        
        key = (tzname, utcOffset, dst)
        tzInfo = TZManager._tzInfos.get(key)
        if not tzInfo:
           tzInfo = TZInfo(tzname, utcOffset, dst)
           TZManager._tzInfos[key] = tzInfo
        return tzInfo
docs: Get / Add timezone info