code: def columns_from_file_list(file_list, columns, ifo, start, end):
      
      file_list = file_list.find_output_with_ifo(ifo)
      file_list = file_list.find_all_output_in_range(ifo, segment(start, end))
  
      trig_dict = {}
      for trig_file in file_list:
          f = h5py.File(trig_file.storage_path, 'r')
  
          time = f['end_time'][:]
          pick = numpy.logical_and(time < end, time > start)
          pick_loc = numpy.where(pick)[0]
  
          for col in columns:
              if col not in trig_dict:
                  trig_dict[col] = []
              trig_dict[col] = numpy.concatenate([trig_dict[col], f[col][:][pick_loc]])
  
      return trig_dict
docs: Return columns of information stored in single detector trigger
      files.
  
      Parameters
      ----------
      file_list_file : string
          pickle file containing the list of single detector
      triggers.
      ifo : string
          The ifo to return triggers for.
      columns : list of strings
          The list of columns to read from the trigger files.
      start : int
          The start time to get triggers from
      end : int
          The end time to get triggers from
  
      Returns
      -------
      trigger_dict : dict
          A dictionary of column vectors with column names as keys.