Add sorting to a namedtuple
You could use multiple inheritance:

@functools.total_ordering
class SubtitleOrdering(object):
    def __eq__(self, other): return self.start == other.start
    def __lt__(self, other): return self.start &lt;  other.start

class Subtitle(SubtitleOrdering, namedtuple('Subtitle', ['index', 'start', 'end', 'content'])):
    pass


total_ordering works normally on SubtitleOrdering, and making it the first base class overrides the comparison methods of the namedtuple.