code: def one_of_k_encoding_unk(x, allowable_set):
      """Maps inputs not in the allowable set to the last element.
  
      Unlike `one_of_k_encoding`, if `x` is not in `allowable_set`, this method
      pretends that `x` is the last element of `allowable_set`.
  
      Parameters
      ----------
      x: object
          Must be present in `allowable_set`.
      allowable_set: list
          List of allowable quantities.
  
      Examples
      --------
      >>> dc.feat.graph_features.one_of_k_encoding_unk("s", ["a", "b", "c"])
      [False, False, True]
  
      """
      if x not in allowable_set:
          x = allowable_set[-1]
      return list(map(lambda s: x == s, allowable_set))
  
imports: import numpy
  import deepchem
  from deepchem.feat.base_classes import MolecularFeaturizer
  from deepchem.feat.mol_graphs import ConvMol, WeaveMol
  from deepchem.data import DiskDataset
  import logging
  from typing import Optional, List, Tuple, Union, Iterable
  from deepchem.utils.typing import RDKitMol, RDKitAtom
  from deepchem.utils.molecule_feature_utils import one_hot_encode
label_desc: Use image node_id 2 for calling a global function with example usage: one_of_k_encoding_unk(x, allowable_set) and returns: list