class_docstr: Transformer that performs regression to build relationship between a
  target series and the rest of series, and returns regression residual
  series.
  
  Parameters
  ----------
  regressor: object
      Regressor to be used. Same as a scikit-learn regressor, it should
      minimally have `fit` and `predict` methods.
  target: str, optional
      Name of the column to be regarded as target variable.
code: def _param_names(self) -> Tuple[str, ...]:
      return ("regressor", "target")
  
imports: from typing import Any, Callable, Dict, Optional, Tuple, Union
  import pandas
  from sklearn.decomposition import PCA
  from .._transformer_base import _NonTrainableMultivariateTransformer, _TrainableMultivariateTransformer
label_desc: Use image node_id 2 for calling the RegressionResidual obj's underlying member method code with example usage: obj._param_names() and returns: str,  str