What is the method to invoke a fetch function onReceive for instant display of a Firebase update on the user interface?

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The method to invoke a fetch function onReceive for instant display of a Firebase update on the user interface is to use the Firebase real-time database SDK to listen for changes in the database, and then update the UI as soon as a change is detected. This can be done by attaching a listener to a Firebase reference using the on() method, and then calling a function to update the UI with the new data whenever an event (e.g. child_added, child_changed, etc.) is triggered by the listener. This will ensure that the UI is always up-to-date with the latest data from the Firebase database.