docs: def get(self, segment_def_id = None):
  		"""
  		Return a segmentlist object describing the times spanned by
  		the segments carrying the given segment_def_id.  If
  		segment_def_id is None then all segments are returned.
  
  		Note:  the result is not coalesced, the segmentlist
  		contains the segments as they appear in the table.
  		"""
  		if segment_def_id is None:
  			return segments.segmentlist(row.segment for row in self)
  		return segments.segmentlist(row.segment for row in self if row.segment_def_id == segment_def_id)