Returns the database associated with this tree widget.
        
        :return     <orb.Database> || None

def database(self):
        """
        Returns the database associated with this tree widget.
        
        :return     <orb.Database> || None
        """
        if self._database:
            return self._database
        if self._recordSet is not None:
            return self._recordSet.database()
        else:
            return Orb.instance().database()