How to add effect to FCP XML?

I tried both methods and it didn’t work

1.

timeline.clip.effects.append(effect)

2.

timeline.clip.metadata['fcp_xml']['filter'].append(effect)

Start by tracing the timeline.clip.effects and timeline.clip.metadata['fcp_xml']['filter'] entry points used in the report, then consult the OpenTimelineIO API documentation or source for FCP XML effect handling. Done means identifying a supported way to add an effect, or documenting the missing behavior with a reproducible example and an appropriate test.

Written by the indexing model from the issue text.