code: def calculate_term_frequencies(self):
  		
  		for doc in self.processed_corpus:
  			term_frequency_doc = defaultdict(int)
  			for word in doc:
  				term_frequency_doc[word] += 1
  			
  			for key,value in term_frequency_doc.iteritems():
  				term_frequency_doc[key] = (1.0 * value) / len(doc)
  			self.term_frequencies.append(term_frequency_doc)
docs: Q.calculate_term_frequencies() -- calculate the number of times 
  		each term t occurs in document d.