Returns a new query for this instance with Query.Function.Lower as
        a function option.
        
        :return     <Query>

def lower(self):
        """
        Returns a new query for this instance with Query.Function.Lower as
        a function option.
        
        :return     <Query>
        """
        q = self.copy()
        q.addFunction(Query.Function.Lower)
        return q