code: def _D_objective(self, neg_pairs, w):
      return np.log(
          np.sum(
              np.sqrt(
                  np.sum(
                      ((neg_pairs[:, 0, :] - neg_pairs[:, 1, :]) ** 2)
                      * w[None, :],
                      axis=1,
                  )
                  + 1e-6
              )
          )
      )
  
imports: import numpy
  from sklearn.base import TransformerMixin
  from sklearn.utils.validation import assert_all_finite
  from .base_metric import _PairsClassifierMixin, MahalanobisMixin
  from .constraints import Constraints, wrap_pairs
  from ._util import components_from_metric, _initialize_metric_mahalanobis
  import warnings
label_desc: Use image node_id 9 for calling the _BaseMMC obj's underlying member method code with example usage: obj._D_objective(neg_pairs, w) and returns: np