code: def pair(self, pair):
          '''Add a *pair* to the structure.'''
          if len(pair) == 1:
              # if only one value is passed, the value must implement a
              # score function which retrieve the first value of the pair
              # (score in zset, timevalue in timeseries, field value in
              # hashtable)
              return (pair[0].score(), pair[0])
          elif len(pair) != 2:
              raise TypeError('add expected 2 arguments, got {0}'
                              .format(len(pair)))
          else:
              return paif pair(self, pair):
          '''Add a *pair* to the structure.'''
          if len(pair) == 1:
              # if only one value is passed, the value must implement a
              # score function which retrieve the first value of the pair
              # (score in zset, timevalue in timeseries, field value in
              # hashtable)
              return (pair[0].score(), pair[0])
          elif len(pair) != 2:
              raise TypeError('add expected 2 arguments, got {0}'
                              .format(len(pair)))
          else:
              return pair
docs: Add a *pair* to the structure.