Convert the posterior to an xarray dataset.

def posterior_to_xarray(self):
        """Convert the posterior to an xarray dataset."""
        # Do not make pyro a requirement
        from pyro.infer import EmpiricalMarginal

        try:  # Try pyro>=0.3 release syntax
            data = {
                name: np.expand_dims(samples.enumerate_support().squeeze(), 0)
                if self.posterior.num_chains == 1
                else samples.enumerate_support().squeeze()
                for name, samples in self.posterior.marginal(
                    sites=self.latent_vars
                ).empirical.items()
            }
        except AttributeError:  # Use pyro<0.3 release syntax
            data = {}
            for var_name in self.latent_vars:
                # pylint: disable=no-member
                samples = EmpiricalMarginal(
                    self.posterior, sites=var_name
                ).get_samples_and_weights()[0]
                data[var_name] = np.expand_dims(samples.numpy().squeeze(), 0)
        return dict_to_dataset(data, library=self.pyro, coords=self.coords, dims=self.dims)