@abstractmethod<EOL><INDENT>def next(self):<DEDENT>
:returns:     The next record from the dataset.  The returned record object
              is of the same structure as returned by
              :meth:`nupic.data.record_stream.RecordStreamIface.getNextRecord`.
              Returns ``None`` if the next record is not available yet.

:raises: (StopIteration) if a hard "end of file" has been reached
              and no more records will be forthcoming.