class_docstr: Splitter that adds the train sets to the test sets.
  
  Takes a splitter ``cv`` and modifies it in the following way:
  The i-th train sets is identical to the i-th train set of ``cv``.
  The i-th test set is the union of the i-th train set and i-th test set of ``cv``.
  
  Parameters
  ----------
  cv : BaseSplitter
      splitter to modify as above
  
  Examples
  --------
  >>> from sktime.datasets import load_airline
  >>> from sktime.split import ExpandingWindowSplitter
  
  >>> y = load_airline()
  >>> y_template = y[:60]
  >>> cv_tpl = ExpandingWindowSplitter(fh=[2, 4], initial_window=24, step_length=12)
  
  >>> splitter = TestPlusTrainSplitter(cv_tpl)
docstr: Return testing parameter settings for the splitter.
  
  Parameters
  ----------
  parameter_set : str, default="default"
      Name of the set of test parameters to return, for use in tests. If no
      special parameters are defined for a value, will return `"default"` set.
  
  Returns
  -------
  params : dict or list of dict, default = {}
      Parameters to create testing instances of the class
      Each dict are parameters to construct an "interesting" test instance, i.e.,
      `MyClass(**params)` or `MyClass(**params[i])` creates a valid test instance.
      `create_test_instance` uses the first (or only) dictionary in `params`
code: def get_test_params(cls, parameter_set="default"):
      """Return testing parameter settings for the splitter.
  
      Parameters
      ----------
      parameter_set : str, default="default"
          Name of the set of test parameters to return, for use in tests. If no
          special parameters are defined for a value, will return `"default"` set.
  
      Returns
      -------
      params : dict or list of dict, default = {}
          Parameters to create testing instances of the class
          Each dict are parameters to construct an "interesting" test instance, i.e.,
          `MyClass(**params)` or `MyClass(**params[i])` creates a valid test instance.
          `create_test_instance` uses the first (or only) dictionary in `params`
      """
      from sktime.split import (
          ExpandingWindowSplitter,
          SingleWindowSplitter,
      )
  
      cv_1 = ExpandingWindowSplitter(
          fh=[2, 4], initial_window=24, step_length=12
      )
      cv_2 = SingleWindowSplitter(fh=[2, 4], window_length=24)
      return [{"cv": cv_1}, {"cv": cv_2}]
  
file_path: sktime/sktime/split/testplustrain.py
imports: from typing import Optional
  import numpy
  import pandas
  from sktime.split.base import BaseSplitter
  from sktime.split.base._common import ACCEPTED_Y_TYPES, SPLIT_GENERATOR_TYPE
label_desc: Use image node_id 5 for calling the TestPlusTrainSplitter obj's underlying member method code with example usage: obj.get_test_params(cls, parameter_set) and returns: list