Returns distance between the site and a point in space.

        Args:
            pt: Cartesian coordinates of point.

        Returns:
            Distance (float)

def distance_from_point(self, pt):
        """
        Returns distance between the site and a point in space.

        Args:
            pt: Cartesian coordinates of point.

        Returns:
            Distance (float)
        """
        return np.linalg.norm(np.array(pt) - self.coords)