class_docstr: MACCS Keys Fingerprint.
  
  The MACCS (Molecular ACCess System) keys are one of the most commonly used structural keys.
  Please confirm the details in [1]_, [2]_.
  
  Examples
  --------
  >>> import deepchem as dc
  >>> smiles = 'CC(=O)OC1=CC=CC=C1C(=O)O'
  >>> featurizer = dc.feat.MACCSKeysFingerprint()
  >>> features = featurizer.featurize([smiles])
  >>> type(features[0])
  <class 'numpy.ndarray'>
  >>> features[0].shape
  (167,)
  
  References
  ----------
  .. [1] Durant, Joseph L., et al. "Reoptimization of MDL keys for use in drug discovery."
           Journal of chemical information and computer sciences 42.6 (2002): 1273-1280.
  .. [2] https://github.com/rdkit/rdkit/blob/master/rdkit/Chem/MACCSkeys.py
  
  Note
  ----
  This class requires RDKit to be installed.
docstr: Calculate MACCS keys fingerprint.
  
  Parameters
  ----------
  datapoint: rdkit.Chem.rdchem.Mol
          RDKit Mol object
  
  Returns
  -------
  np.ndarray
          1D array of RDKit descriptors for `mol`. The length is 167.
docstr_tok: ["Calculate","MACCS","keys","fingerprint",".","Parameters","--","--","--","--","--","datapoint",":","rdkit.Chem.rdchem.Mol","RDKit","Mol","object","Returns","--","--","--","-","np.ndarray","1D","array","of","RDKit","descriptors","for","`","mol","`",".","The","length","is","167","."]
code: def _featurize(self, datapoint: RDKitMol, **kwargs) -> np.ndarray:
      """
      Calculate MACCS keys fingerprint.
  
      Parameters
      ----------
      datapoint: rdkit.Chem.rdchem.Mol
              RDKit Mol object
  
      Returns
      -------
      np.ndarray
              1D array of RDKit descriptors for `mol`. The length is 167.
  
      """
      if "mol" in kwargs:
          datapoint = kwargs.get("mol")
          raise DeprecationWarning(
              'Mol is being phased out as a parameter, please pass "datapoint" instead.'
          )
  
      if self.calculator is None:
          try:
              from rdkit.Chem.AllChem import GetMACCSKeysFingerprint
  
              self.calculator = GetMACCSKeysFingerprint
          except ModuleNotFoundError:
              raise ImportError(
                  "This class requires RDKit to be installed."
              )
  
      return self.calculator(datapoint)
  
imports: import numpy
  from deepchem.utils.typing import RDKitMol
  from deepchem.feat.base_classes import MolecularFeaturizer
label_desc: Use image node_id 2 for calling the MACCSKeysFingerprint obj's underlying member method code with example usage: obj._featurize(datapoint) and returns: self