Determines if point pp is in the plane within the tolerance dist_tolerance
        :param pp: point to be tested
        :param dist_tolerance: tolerance on the distance to the plane within which point pp is considered in the plane
        :return: True if pp is in the plane, False otherwise

def is_in_plane(self, pp, dist_tolerance):
        """
        Determines if point pp is in the plane within the tolerance dist_tolerance
        :param pp: point to be tested
        :param dist_tolerance: tolerance on the distance to the plane within which point pp is considered in the plane
        :return: True if pp is in the plane, False otherwise
        """
        return np.abs(np.dot(self.normal_vector, pp) + self._coefficients[3]) <= dist_tolerance