code: def drop_unused_terms(self):
  		'''
  		Returns
  		-------
  		PriorFactory
  		'''
  		self.term_doc_mat = self.term_doc_mat.remove_terms(
  			set(self.term_doc_mat.get_terms()) - set(self.priors.index)
  		)
  		self._reindex_priors()
  		return self drop_unused_terms(self):
  		'''
  		Returns
  		-------
  		PriorFactory
  		'''
  		self.term_doc_mat = self.term_doc_mat.remove_terms(
  			set(self.term_doc_mat.get_terms()) - set(self.priors.index)
  		)
  		self._reindex_priors()
  		return self
docs: Returns
  		-------
  		PriorFactory