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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 async def get_supported_playback_functions( self, uri="" ) -> List[SupportedFunctions]: """Return list of inputs and their supported functions."""

        return [
            SupportedFunctions.make(**x)
            for x in await self.services["avContent"]["getSupportedPlaybackFunction"](
                uri=uri
            )
        ]