Show example of async event handler

[rdong8]

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The example seems to define an async handler but never shows how to use it.

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Is the documentation missing? Or is it confusing? Why is it confusing?

Documentation is missing.

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Show how to use the async handler and document it in the Supabase Python documentation.

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[silentworks]

Event handlers are sync. I think we forgot to remove that one from the example code.