Tuple conversion to (value, dimensions), e.g.:
         (123, {dimension_1: "foo", dimension_2: "bar"})

def tuple(self):
        """ Tuple conversion to (value, dimensions), e.g.:
         (123, {dimension_1: "foo", dimension_2: "bar"})
        """
        return (self.value, {dv.id: dv.value for dv in self.dimensionvalues})