code: def dual_gap_(self):
      self._gap = None
  
imports: import numbers
  import numpy
  from scipy import sparse
  from sklearn.linear_model._coordinate_descent import ElasticNet
  from sklearn.linear_model._coordinate_descent import Lasso
  from sklearn.utils import check_array, check_X_y
  import daal4py
  from daal4py.sklearn._utils import PatchingConditionsChain, control_n_jobs, get_patch_message, getFPType, make2d, run_with_n_jobs, sklearn_check_version
  import logging
  import warnings
  from sklearn.exceptions import ConvergenceWarning
  from sklearn.preprocessing import normalize
  from .._device_offload import support_usm_ndarray
label_desc: Use image node_id 4 for calling the ElasticNet obj's underlying member method code with example usage: obj.dual_gap_() without return types