Return potential data for a given measurement configuration.

        Parameters
        ----------
        config_nr: int
            Number of the configurations. Starts at 0

        Returns
        -------
        pot_data: list with two numpy.ndarrays
            First array: magnitude potentials, second array: phase potentials

def get_potential(self, config_nr):
        """Return potential data for a given measurement configuration.

        Parameters
        ----------
        config_nr: int
            Number of the configurations. Starts at 0

        Returns
        -------
        pot_data: list with two numpy.ndarrays
            First array: magnitude potentials, second array: phase potentials

        """
        if self.assignments['potentials'] is None:
            self._check_state()
            if self.can_model:
                self.model(potentials=True)

        nids = self.assignments['potentials'][config_nr]
        pot_data = [self.nodeman.nodevals[nid] for nid in nids]
        return pot_data