code: def start_time_distance(item_a, item_b, max_value):
      
      start_time_diff = np.abs(item_a.times[0] - item_b.times[0])
      return np.minimum(start_time_diff, max_value) / float(max_value)
docs: Absolute difference between the starting times of each item.
  
      Args:
          item_a: STObject from the first set in TrackMatcher
          item_b: STObject from the second set in TrackMatcher
          max_value: Maximum distance value used as scaling value and upper constraint.
  
      Returns:
          Distance value between 0 and 1.