code: def _test_masks(self):
      if self.fold_assignments is None:
          self._assign_folds()
      if self.masks is None:
          self.masks = [
              i == self.fold_assignments for i in range(self.n_folds)
          ]
      return self.masks
  
file_path: h2o-3/h2o-py/h2o/cross_validation.py
imports: from h2o.utils.compatibility import *
label_desc: Use image node_id 3 for calling the H2OKFold obj's underlying member method code with example usage: obj._test_masks() and returns: self