class_docstr: Transformer base class.
class_docstr_tok: ["Transformer","base","class","."]
docstr: Update transformer with X and y.
  
  private _update containing the core logic, called from update
  
  Parameters
  ----------
  X : Series or Panel of mtype X_inner_mtype
      if X_inner_mtype is list, _update must support all types in it
      Data to update transformer with
  y : Series or Panel of mtype y_inner_mtype, default=None
      Additional data, e.g., labels for tarnsformation
  
  Returns
  -------
  self: a fitted instance of the estimator
  
  See extension_templates/transformer.py for implementation details.
code: def _update(self, X, y=None):
      """Update transformer with X and y.
  
      private _update containing the core logic, called from update
  
      Parameters
      ----------
      X : Series or Panel of mtype X_inner_mtype
          if X_inner_mtype is list, _update must support all types in it
          Data to update transformer with
      y : Series or Panel of mtype y_inner_mtype, default=None
          Additional data, e.g., labels for tarnsformation
  
      Returns
      -------
      self: a fitted instance of the estimator
  
      See extension_templates/transformer.py for implementation details.
      """
      # standard behaviour: no update takes place, new data is ignored
      return self
  
imports: from itertools import product
  from typing import Union
  import numpy
  import pandas
  from sktime.base import BaseEstimator
  from sktime.datatypes import VectorizedDF, check_is_error_msg, check_is_mtype, check_is_scitype, convert, convert_to, mtype_to_scitype, update_data
  from sktime.datatypes._series_as_panel import convert_to_scitype
  from sktime.utils.sklearn import is_sklearn_classifier, is_sklearn_clusterer, is_sklearn_regressor, is_sklearn_transformer
  from sktime.utils.validation._dependencies import _check_estimator_deps
label_desc: Use image node_id 23 for calling the BaseTransformer obj's underlying member method code with example usage: obj._update(X, y) and returns: self