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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def registerTzinfo(obj, tzinfo):
 """ Register tzinfo if it's not already registered, return its tzid. """

        tzid = obj.pickTzid(tzinfo)
        if tzid and not getTzid(tzid, False):
            registerTzid(tzid, tzinfo)
        return tzid