Fixing Python2.7 build error

import numpy as np

import tensorflow as tf

import copy

import six

from deepchem.metrics import to_one_hot, from_one_hot

from deepchem.models.tensorgraph.layers import Dense, Concat, SoftMax, \

    A tf.py_func wrapper is written around this when creating the input_fn for make_estimator

    """

    if isinstance(ids_b[0], bytes):

    if isinstance(

        ids_b[0],

        bytes) and not six.PY2:  # Python 2.7 bytes and string are analogous

      ids_b = [TextCNNModel.convert_bytes_to_char(smiles) for smiles in ids_b]

    smiles_seqs = [self.smiles_to_seq(smiles) for smiles in ids_b]

    smiles_seqs = np.vstack(smiles_seqs)