code: def cv_split(cv, X, y, groups, is_pairwise, cache):
      check_consistent_length(X, y, groups)
      return CVCache(
          list(cv.split(X, y, groups)),
          is_pairwise,
          cache,
          _num_samples(X),
      )
  
imports: from __future__ import absolute_import, division, print_function
  import warnings
  from collections import defaultdict
  from threading import Lock
  from timeit import default_timer
  import numpy
  import packaging.version
  from dask.base import normalize_token
  from scipy import sparse
  from scipy.stats import rankdata
  from sklearn.exceptions import FitFailedWarning
  from sklearn.pipeline import FeatureUnion, Pipeline
  from sklearn.utils.validation import check_consistent_length
  from toolz import pluck
  from .._compat import Mapping
  from .utils import _index_param_value, _num_samples, _safe_indexing, copy_estimator
label_desc: Use image node_id 2 for calling a global function with example usage: cv_split(cv, X, y, groups, is_pairwise, cache) and returns: CVCache