Convert prior_predictive samples to xarray.

def prior_predictive_to_xarray(self):
        """Convert prior_predictive samples to xarray."""
        prior_predictive = self.prior_predictive

        if (
            isinstance(prior_predictive, (tuple, list)) and prior_predictive[0].endswith(".csv")
        ) or (isinstance(prior_predictive, str) and prior_predictive.endswith(".csv")):
            if isinstance(prior_predictive, str):
                prior_predictive = [prior_predictive]
            chain_data = []
            for path in prior_predictive:
                parsed_output = _read_output(path)
                for sample, *_ in parsed_output:
                    chain_data.append(sample)
            data = _unpack_dataframes(chain_data)
        else:
            if isinstance(prior_predictive, str):
                prior_predictive = [prior_predictive]
            prior_predictive_cols = [
                col
                for col in self.prior[0].columns
                if any(item == col.split(".")[0] for item in prior_predictive)
            ]
            data = _unpack_dataframes([item[prior_predictive_cols] for item in self.prior])
        return dict_to_dataset(data, coords=self.coords, dims=self.dims)