code: def _get_quad_approx(self, coefa, coefb, objb, gradb, L, penalty):
      approx = objb
      diff = coefa - coefb
      approx += np.sum(diff * gradb)
      approx += L / 2 * np.sum(diff**2)
      approx += self.alpha * penalty.regularization(coefa)
      return approx
  
imports: import numpy
  from sklearn.utils.extmath import safe_sparse_dot
  from .base import BaseClassifier, BaseRegressor
  from .dataset_fast import get_dataset
  from .loss_fast import Squared
  from .loss_fast import SquaredHinge
  from .loss_fast import MulticlassSquaredHinge
  from .loss_fast import MulticlassLog
  from .penalty import L1Penalty
  from .penalty import L1L2Penalty
  from .penalty import TracePenalty
  from .penalty import SimplexConstraint
  from .penalty import L1BallConstraint
  from .penalty import TotalVariation1DPenalty
label_desc: Use image node_id 4 for calling the _BaseFista obj's underlying member method code with example usage: obj._get_quad_approx(coefa, coefb, objb, gradb, L, penalty) and returns: approx