Get distance between site i and j assuming periodic boundary
        conditions. If the index jimage of two sites atom j is not specified it
        selects the jimage nearest to the i atom and returns the distance and
        jimage indices in terms of lattice vector translations if the index
        jimage of atom j is specified it returns the distance between the i
        atom and the specified jimage atom.

        Args:
            i (int): Index of first site
            j (int): Index of second site
            jimage: Number of lattice translations in each lattice direction.
                Default is None for nearest image.

        Returns:
            distance

def get_distance(self, i, j, jimage=None):
        """
        Get distance between site i and j assuming periodic boundary
        conditions. If the index jimage of two sites atom j is not specified it
        selects the jimage nearest to the i atom and returns the distance and
        jimage indices in terms of lattice vector translations if the index
        jimage of atom j is specified it returns the distance between the i
        atom and the specified jimage atom.

        Args:
            i (int): Index of first site
            j (int): Index of second site
            jimage: Number of lattice translations in each lattice direction.
                Default is None for nearest image.

        Returns:
            distance
        """
        return self[i].distance(self[j], jimage)