pcmill

import csv

file = open('sentences.txt', 'r', encoding="utf8")
book = file.read()

def tokenize():
    if book is not None:
        words = book.lower().split()
        return words
    else:

pcmill

file = open('sentences.txt', 'r', encoding="utf8")
sentences = file.read()

def tokenize():
    if sentences is not None:
        words = sentences.lower().split()
        return words
    else:
        return None