Q.process_corpus() -- processes the queries defined by us, 
		by tokenizing, stemming, and removing stop words.

def process_corpus(self):
		"""Q.process_corpus() -- processes the queries defined by us, 
		by tokenizing, stemming, and removing stop words.
		"""
		for doc in self.corpus_list:
			doc = wt(doc)
			sentence = []
			for word in doc:
				if word not in self.stop_words and word not in self.punctuation:
					word = self.stemmer.stem(word)
					sentence.append(word)
			self.processed_corpus.append(sentence)