def segmentPositionSortKey(self, segment):
return segment.cell + (segment._ordinal / float(self._nextSegmentOrdinal))<EOL>
Return a numeric key for sorting this segment. This can be used with the 
python built-in ``sorted()`` function.

:param segment: (:class:`Segment`) within this :class:`Connections` 
       instance.
:returns: (float) A numeric key for sorting.