docstr: Calculate Score
  
  If the estimator is not fitted, then raise NotFittedError
code: def score(self, X, y):
      """
      Calculate Score
  
      If the estimator is not fitted, then raise NotFittedError
      """
      check_is_fitted(self)
      # Perform scoring logic
      return 0.5
  
file_path: scikit-learn/examples/developing_estimators/sklearn_is_fitted.py
imports: from sklearn.base import BaseEstimator, ClassifierMixin
  from sklearn.utils.validation import check_is_fitted
label_desc: Use image node_id 4 for calling the CustomEstimator obj's underlying member method code with example usage: obj.score(X, y) and returns: int