code: def get_expr_id(self, search_group, search, lars_id, instruments, gps_start_time, gps_end_time, comments = None):
  		
  		# create string from instrument set
  		instruments = ifos_from_instrument_set(instruments)
  
  		# look for the ID
  		for row in self:
  			if (row.search_group, row.search, row.lars_id, row.instruments, row.gps_start_time, row.gps_end_time, row.comments) == (search_group, search, lars_id, instruments, gps_start_time, gps_end_time, comments):
  				# found it
  				return row.experiment_id
  
  		# experiment not found in table
  		return None
docs: Return the expr_def_id for the row in the table whose
  		values match the givens.
  		If a matching row is not found, returns None.
  
  		@search_group: string representing the search group (e.g., cbc)
  		@serach: string representing search (e.g., inspiral)
  		@lars_id: string representing lars_id
  		@instruments: the instruments; must be a python set
  		@gps_start_time: string or int representing the gps_start_time of the experiment
  		@gps_end_time: string or int representing the gps_end_time of the experiment