Я думаю, что вы хотите достичь, чтобы расширить список игнорируемых слов из NLTK. Поскольку стоп-слова в NLTK хранятся в одном списке, вы можете просто сделать это:
>>> from nltk.corpus import stopwords
>>> stoplist = stopwords.words('english')
>>> stoplist
[u'i', u'me', u'my', u'myself', u'we', u'our', u'ours', u'ourselves', u'you', u'your', u'yours', u'yourself', u'yourselves', u'he', u'him', u'his', u'himself', u'she', u'her', u'hers', u'herself', u'it', u'its', u'itself', u'they', u'them', u'their', u'theirs', u'themselves', u'what', u'which', u'who', u'whom', u'this', u'that', u'these', u'those', u'am', u'is', u'are', u'was', u'were', u'be', u'been', u'being', u'have', u'has', u'had', u'having', u'do', u'does', u'did', u'doing', u'a', u'an', u'the', u'and', u'but', u'if', u'or', u'because', u'as', u'until', u'while', u'of', u'at', u'by', u'for', u'with', u'about', u'against', u'between', u'into', u'through', u'during', u'before', u'after', u'above', u'below', u'to', u'from', u'up', u'down', u'in', u'out', u'on', u'off', u'over', u'under', u'again', u'further', u'then', u'once', u'here', u'there', u'when', u'where', u'why', u'how', u'all', u'any', u'both', u'each', u'few', u'more', u'most', u'other', u'some', u'such', u'no', u'nor', u'not', u'only', u'own', u'same', u'so', u'than', u'too', u'very', u's', u't', u'can', u'will', u'just', u'don', u'should', u'now']
>>> more_stopwords = """with some your just have from it's /via & that they your there this into providing would can't"""
>>> stoplist += more_stopwords.split()
>>> sent = "With some of hacks to your line of code , we can simply extract the data you need ."
>>> sent_with_no_stopwords = [word for word in sent.split() if word not in stoplist]
>>> sent_with_no_stopwords
['With', 'hacks', 'line', 'code', ',', 'simply', 'extract', 'data', 'need', '.']
# Note that the "With" is different from "with".
# So let's try this:
>>> sent_with_no_stopwords = [word for word in sent.lower().split() if word not in stoplist]
>>> sent_with_no_stopwords
['hacks', 'line', 'code', ',', 'simply', 'extract', 'data', 'need', '.']
# To get it back into a string:
>>> new_sent = " ".join(sent_with_no_stopwords)
>>> new_sent
'hacks line code , simply extract data need .'