code: def indexable(*iterables):
      
      result = []
      for X in iterables:
          if sp.issparse(X):
              result.append(X.tocsr())
          elif hasattr(X, "__getitem__") or hasattr(X, "iloc"):
              result.append(X)
          elif X is None:
              result.append(X)
          else:
              result.append(np.array(X))
      check_consistent_length(*result)
      return result
docs: Make arrays indexable for cross-validation.
  
      Checks consistent length, passes through None, and ensures that everything
      can be indexed by converting sparse matrices to csr and converting
      non-interable objects to arrays.
  
      Parameters
      ----------
      iterables : lists, dataframes, arrays, sparse matrices
          List of objects to ensure sliceability.