code: def _assess_approximation(self, boundary_points, derivs, funcs, nodes, problem):
          
          interior_residuals = self._compute_interior_residuals(derivs, funcs,
                                                                nodes, problem)
          boundary_residuals = self._compute_boundary_residuals(boundary_points,
                                                                funcs, problem)
          return np.hstack(interior_residuals + boundary_residuals)
docs: Parameters
          ----------
          basis_derivs : list(function)
          basis_funcs : list(function)
          problem : TwoPointBVPLike
  
          Returns
          -------
          resids : numpy.ndarray