class_docstr: Base class for defining estimators in sktime.
  
  Extends sktime's BaseObject to include basic functionality for fittable estimators.
class_docstr_tok: ["Base","class","for","defining","estimators","in","sktime",".","Extends","sktime","'s","BaseObject","to","include","basic","functionality","for","fittable","estimators","."]
docstr: Whether `fit` has been called.
docstr_tok: ["Whether","`","fit","`","has","been","called","."]
code: def is_fitted(self):
      """Whether `fit` has been called."""
      return self._is_fitted
  
imports: import warnings
  from copy import deepcopy
  from skbase.base import BaseObject
  from sklearn import clone
  from sklearn.base import BaseEstimator
  from sktime.exceptions import NotFittedError
  from sktime.utils.random_state import set_random_state
label_desc: Use image node_id 2 for calling the BaseEstimator obj's underlying member method code with example usage: obj.is_fitted() and returns: self