add BasicSmilesTokenizer class

                writer.write(token + u"\n")

                index += 1

        return (vocab_file,)

class BasicSmilesTokenizer(object):

    """Run basic SMILES tokenization"""

    def __init__(self, regex_pattern=SMI_REGEX_PATTERN):

        """ Constructs a BasicSMILESTokenizer.

        Args:

            **regex**: SMILES token regex

        """

        self.regex_pattern = regex_pattern

        self.regex = re.compile(self.regex_pattern)

    def tokenize(self, text):

        """ Basic Tokenization of a SMILES.

        """

        tokens = [token for token in self.regex.findall(text)]

        return tokens