The Sequence type (link) is too broadly defined as it accepts as input list[Any]. It isn't defined in the CZML wiki, and the only use case I can see for it is for defining a list of TimeIntervals (e.g. here) or a list of IntervalValues (e.g. here).
It seems more appropriate to replace the Sequence class with either:
SequenceTime (or something similar) class that accepts list[TimeInterval] | list[IntervalValue]
SequenceTimeInterval class and SequenceIntervalValue class
My preference is for option 1.
As a side note I think many people will get this class confused with the Sequence class from collections.abc.
@astrojuanlu let me know your thoughts and I'll submit a PR (along with some other bug fixes I've found recently).