add docstring for regex

from transformers import BertTokenizer

# export

SMI_REGEX_PATTERN = r"(\[[^\]]+]|Br?|Cl?|N|O|S|P|F|I|b|c|n|o|s|p|\(|\)|\.|=|#|-|\+|\\|\/|:|~|@|\?|>>?|\*|\$|\%[0-9]{2}|[0-9])"

SMI_REGEX_PATTERN = r"""(\[[^\]]+]|Br?|Cl?|N|O|S|P|F|I|b|c|n|o|s|p|\(|\)|\.|=|

#|-|\+|\\|\/|:|~|@|\?|>>?|\*|\$|\%[0-9]{2}|[0-9])"""

def get_default_tokenizer():

    default_vocab_path = (

class SmilesTokenizer(BertTokenizer):

    """

    Constructs a SmilesTokenizer.

    Bulk of code is from https://github.com/huggingface/transformers and https://github.com/rxn4chemistry/rxnfp

    Constructs a SmilesTokenizer. The tokenizer heavily inherits from the BERT

    WordPieceTokenizer implementation found in Huggingface's transformers library.

    Please see https://github.com/huggingface/transformers

    and https://github.com/rxn4chemistry/rxnfp for more details.

    References

    ----------

            **kwargs

    ):

        """Constructs a BertTokenizer.

        """Constructs a SmilesTokenizer.

        Parameters

        ----------