function callRevealApi( methodName, methodArguments, callId ) {

		let result = deck[methodName].apply( deck, methodArguments );
		speakerWindow.postMessage( JSON.stringify( {
			namespace: 'reveal-notes',
			type: 'return',
			result,
			callId
		} ), '*' );

	}
Calls the specified Reveal.js method with the provided argument
and then pushes the result to the notes frame.