How to use the autofit.mapper.prior.GaussianPrior function in autofit

self.lens_galaxies.lens.light.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.light.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.light.axis_ratio = prior.GaussianPrior(mean=0.8, sigma=0.15)
        self.lens_galaxies.lens.light.phi = prior.GaussianPrior(mean=45.0, sigma=15.0)
        self.lens_galaxies.lens.light.intensity = prior.GaussianPrior(mean=0.02, sigma=0.01)
        self.lens_galaxies.lens.light.effective_radius = prior.GaussianPrior(mean=0.62, sigma=0.2)
        self.lens_galaxies.lens.light.sersic_index = prior.GaussianPrior(mean=4.0, sigma=2.0)

        self.lens_galaxies.lens.mass.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.mass.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.mass.axis_ratio = prior.GaussianPrior(mean=0.8, sigma=0.25)
        self.lens_galaxies.lens.mass.phi = prior.GaussianPrior(mean=45.0, sigma=30.0)
        self.lens_galaxies.lens.mass.einstein_radius = prior.GaussianPrior(mean=0.8, sigma=0.1)

        self.source_galaxies.source.light.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.source_galaxies.source.light.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.source_galaxies.source.light.axis_ratio = prior.GaussianPrior(mean=0.8, sigma=0.1)
        self.source_galaxies.source.light.phi = prior.GaussianPrior(mean=90.0, sigma=10.0)
        self.source_galaxies.source.light.intensity = prior.GaussianPrior(mean=0.14, sigma=0.05)
        self.source_galaxies.source.light.effective_radius = prior.GaussianPrior(mean=0.12, sigma=0.2)

def pass_priors(self, previous_results):

            self.lens_galaxies.lens.light.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
            self.lens_galaxies.lens.light.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)
            self.lens_galaxies.los0.light.centre_0 = prior.GaussianPrior(mean=4.0, sigma=0.1)
            self.lens_galaxies.los0.light.centre_1 = prior.GaussianPrior(mean=4.0, sigma=0.1)
            self.lens_galaxies.los1.light.centre_0 = prior.GaussianPrior(mean=3.6, sigma=0.1)
            self.lens_galaxies.los1.light.centre_1 = prior.GaussianPrior(mean=-5.3, sigma=0.1)
            self.lens_galaxies.los2.light.centre_0 = prior.GaussianPrior(mean=-3.1, sigma=0.1)
            self.lens_galaxies.los2.light.centre_1 = prior.GaussianPrior(mean=-2.4, sigma=0.1)

def pass_priors(self, previous_results):

        # What I've done here is looked at the results of phase 1, and manually specified a prior for every parameter.
        # If a parameter was fixed in the previous phase, its prior is based around the previous value. Don't worry
        # about the sigma values for now, I've chosen values that I know will ensure reasonable sampling, but we'll
        # cover this later.

        self.lens_galaxies.lens.light.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.light.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.light.axis_ratio = prior.GaussianPrior(mean=0.8, sigma=0.15)
        self.lens_galaxies.lens.light.phi = prior.GaussianPrior(mean=45.0, sigma=15.0)
        self.lens_galaxies.lens.light.intensity = prior.GaussianPrior(mean=0.02, sigma=0.01)
        self.lens_galaxies.lens.light.effective_radius = prior.GaussianPrior(mean=0.62, sigma=0.2)
        self.lens_galaxies.lens.light.sersic_index = prior.GaussianPrior(mean=4.0, sigma=2.0)

        self.lens_galaxies.lens.mass.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.mass.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.mass.axis_ratio = prior.GaussianPrior(mean=0.8, sigma=0.25)
        self.lens_galaxies.lens.mass.phi = prior.GaussianPrior(mean=45.0, sigma=30.0)
        self.lens_galaxies.lens.mass.einstein_radius = prior.GaussianPrior(mean=0.8, sigma=0.1)

        self.source_galaxies.source.light.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.source_galaxies.source.light.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.source_galaxies.source.light.axis_ratio = prior.GaussianPrior(mean=0.8, sigma=0.1)
        self.source_galaxies.source.light.phi = prior.GaussianPrior(mean=90.0, sigma=10.0)
        self.source_galaxies.source.light.intensity = prior.GaussianPrior(mean=0.14, sigma=0.05)
        self.source_galaxies.source.light.effective_radius = prior.GaussianPrior(mean=0.12, sigma=0.2)

def pass_priors(self, previous_results):

            # Lets restrict the prior's on the centres around the pixel we know the galaxy's light centre peaks.

            self.lens_galaxies.left_lens.light.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.05)
            self.lens_galaxies.left_lens.light.centre_1 = prior.GaussianPrior(mean=-1.0, sigma=0.05)

            # Given we are only fitting the very central region of the lens galaxy, we don't want to let a parameter 
            # like th Sersic index vary. Lets fix it to 4.0.

            self.lens_galaxies.left_lens.light.sersic_index = 4.0

def pass_priors(self, previous_results):

            self.lens_galaxies.lens.mass.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
            self.lens_galaxies.lens.mass.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)

# about the sigma values for now, I've chosen values that I know will ensure reasonable sampling, but we'll
        # cover this later.

        self.lens_galaxies.lens.light.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.light.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.light.axis_ratio = prior.GaussianPrior(mean=0.8, sigma=0.15)
        self.lens_galaxies.lens.light.phi = prior.GaussianPrior(mean=45.0, sigma=15.0)
        self.lens_galaxies.lens.light.intensity = prior.GaussianPrior(mean=0.02, sigma=0.01)
        self.lens_galaxies.lens.light.effective_radius = prior.GaussianPrior(mean=0.62, sigma=0.2)
        self.lens_galaxies.lens.light.sersic_index = prior.GaussianPrior(mean=4.0, sigma=2.0)

        self.lens_galaxies.lens.mass.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.mass.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.lens_galaxies.lens.mass.axis_ratio = prior.GaussianPrior(mean=0.8, sigma=0.25)
        self.lens_galaxies.lens.mass.phi = prior.GaussianPrior(mean=45.0, sigma=30.0)
        self.lens_galaxies.lens.mass.einstein_radius = prior.GaussianPrior(mean=0.8, sigma=0.1)

        self.source_galaxies.source.light.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.source_galaxies.source.light.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)
        self.source_galaxies.source.light.axis_ratio = prior.GaussianPrior(mean=0.8, sigma=0.1)
        self.source_galaxies.source.light.phi = prior.GaussianPrior(mean=90.0, sigma=10.0)
        self.source_galaxies.source.light.intensity = prior.GaussianPrior(mean=0.14, sigma=0.05)
        self.source_galaxies.source.light.effective_radius = prior.GaussianPrior(mean=0.12, sigma=0.2)

def pass_priors(self, previous_results):

            self.lens_galaxies.lens.light.centre_0 = prior.GaussianPrior(mean=0.0, sigma=0.1)
            self.lens_galaxies.lens.light.centre_1 = prior.GaussianPrior(mean=0.0, sigma=0.1)