docstr: Update contents of `merged_datasets`, `coupled_datasets`, and `leaves` and direct
  traversal of the sub-datasets that compose the current dataset name
code: def _enter(self, path, key, value):
      """Update contents of `merged_datasets`, `coupled_datasets`, and `leaves` and direct
      traversal of the sub-datasets that compose the current dataset name
      """
      #################### Merged Datasets ####################
      if value in MERGED_DATASET_NAMES:
          self.merged_datasets.append(path + (key,))
          _names_for_merge = names_for_merge(value, self.stage)
          return dict(), zip(_names_for_merge, _names_for_merge)
  
      #################### Coupled Datasets ####################
      for coupled_candidate in COUPLED_DATASET_CANDIDATES:
          if value == coupled_candidate[0]:
              self.coupled_datasets.append(path + (key,))
              return dict(), zip(
                  coupled_candidate[1:], coupled_candidate[1:]
              )
  
      #################### Leaf Datasets ####################
      if key:
          self.leaves[path + (key,)] = key
  
      return default_enter(path, key, value)
  
imports: from hyperparameter_hunter.keys.hashing import make_hash_sha256
  from hyperparameter_hunter.space.dimensions import Categorical, RejectedOptional
  from hyperparameter_hunter.utils.boltons_utils import remap, default_visit, default_enter
  from hyperparameter_hunter.utils.general_utils import subdict
  import ast
  from contextlib import suppress
  from inspect import getsource
  import numpy
  import pandas
  from typing import List, Callable, Dict, Union, Tuple
label_desc: Use image node_id 3 for calling the DatasetNameReport obj's underlying member method code with example usage: obj._enter(path, key, value) and returns: default_enter, dict,  zip, dict,  zip