code: def use_neutral_categories(self):
  		'''
  		Returns
  		-------
  		PriorFactory
  		'''
  		term_df = self.term_ranker.get_ranks()
  		self.priors += term_df[[c + ' freq' for c in self._get_neutral_categories()]].sum(axis=1)
  		return self use_neutral_categories(self):
  		'''
  		Returns
  		-------
  		PriorFactory
  		'''
  		term_df = self.term_ranker.get_ranks()
  		self.priors += term_df[[c + ' freq' for c in self._get_neutral_categories()]].sum(axis=1)
  		return self
docs: Returns
  		-------
  		PriorFactory