code: def normalize(self):
          "Return my probabilities; must be down to one variable."
          assert len(self.vars) == 1
          return ProbDist(self.vars[0],
                          dict((k, v) for ((k,), v) in self.cpt.items())f normalize(self):
          "Return my probabilities; must be down to one variable."
          assert len(self.vars) == 1
          return ProbDist(self.vars[0],
                          dict((k, v) for ((k,), v) in self.cpt.items()))
docs: Return my probabilities; must be down to one variable.