code: def add(self, o):
          "Add an observation o to the distribution."
          self.smooth_for(o)
          self.dictionary[o] += 1
          self.n_obs += 1
          self.sampler = Nonf add(self, o):
          "Add an observation o to the distribution."
          self.smooth_for(o)
          self.dictionary[o] += 1
          self.n_obs += 1
          self.sampler = None
docs: Add an observation o to the distribution.