How to use the autogalaxy.galaxy.fit_galaxy.FitGalaxy function in autogalaxy

def fit_for_instance(self, instance):

        fit_y = fit_galaxy.FitGalaxy(
            masked_galaxy_dataset=self.galaxy_data_y, model_galaxies=instance.galaxies
        )
        fit_x = fit_galaxy.FitGalaxy(
            masked_galaxy_dataset=self.galaxy_data_x, model_galaxies=instance.galaxies
        )

        return fit_y, fit_x

"""
        Determine the fit of a lens galaxy and source galaxy to the masked_imaging in
        this lens.

        Parameters
        ----------
        instance
            A model instance with attributes

        Returns
        -------
        fit: Fit
            A fractional value indicating how well this model fit and the model
            masked_imaging itself
        """
        return fit_galaxy.FitGalaxy(
            masked_galaxy_dataset=self.galaxy_data, model_galaxies=instance.galaxies
        )

def fit_for_instance(self, instance):

        fit_y = fit_galaxy.FitGalaxy(
            masked_galaxy_dataset=self.galaxy_data_y, model_galaxies=instance.galaxies
        )
        fit_x = fit_galaxy.FitGalaxy(
            masked_galaxy_dataset=self.galaxy_data_x, model_galaxies=instance.galaxies
        )

        return fit_y, fit_x