code: def single(self):
          
          records = list(self)
          size = len(records)
          if size == 0:
              return None
          if size != 1:
              warn("Expected a result with a single record, but this result contains %d" % size)
          return records[0]
docs: Obtain the next and only remaining record from this result.
  
          A warning is generated if more than one record is available but
          the first of these is still returned.
  
          :returns: the next :class:`.Record` or :const:`None` if none remain
          :warns: if more than one record is available