docs: def get_by_name(self, name, clip_to_valid = False):
  		"""
  		Retrieve the active segmentlists whose name equals name.
  		The result is a segmentlistdict indexed by instrument.  All
  		segmentlist objects within it will be copies of the
  		contents of this object, modifications will not affect the
  		contents of this object.  If clip_to_valid is True then the
  		segmentlists will be intersected with their respective
  		intervals of validity, otherwise they will be the verbatim
  		active segments.
  
  		NOTE:  the intersection operation required by clip_to_valid
  		will yield undefined results unless the active and valid
  		segmentlist objects are coalesced.
  		"""
  		result = segments.segmentlistdict()
  		for seglist in self:
  			if seglist.name != name:
  				continue
  			segs = seglist.active
  			if clip_to_valid:
  				# do not use in-place intersection
  				segs = segs & seglist.valid
  			for instrument in seglist.instruments:
  				if instrument in result:
  					raise ValueError("multiple '%s' segmentlists for instrument '%s'" % (name, instrument))
  				result[instrument] = segs.copy()
  		return result