move import check to init

from deepchem.feat.atomic_conformation import AtomicConformation

from deepchem.feat.atomic_conformation import AtomicConformationFeaturizer

# tokenizers

try:

  import transformers

  from transformers import BertTokenizer

  from transformers import RobertaTokenizerFast

  from deepchem.feat.smiles_tokenizer import SmilesTokenizer

  from deepchem.feat.smiles_tokenizer import BasicSmilesTokenizer

  from deepchem.feat.roberta_tokenizer import RobertaFeaturizer

except ModuleNotFoundError:

  pass

from deepchem.feat import MolecularFeaturizer

try:

from transformers import RobertaTokenizerFast

except:

  raise Warning('This class requires transformers.')

  pass

from deepchem.utils.typing import RDKitMol

from typing import Dict, List