parse( input, onDone, onError, options ) {

    		if ( typeof onError === 'object' ) {

    			console.warn( 'THREE.GLTFExporter: parse() expects options as the fourth argument now.' );

    			options = onError;

    		}

    		const writer = new GLTFWriter();
    		const plugins = [];

    		for ( let i = 0, il = this.pluginCallbacks.length; i < il; i ++ ) {

    			plugins.push( this.pluginCallbacks[ i ]( writer ) );

    		}

    		writer.setPlugins( plugins );
    		writer.write( input, onDone, options ).catch( onError );

    	}
Parse scenes and generate GLTF output
@param  {Scene or [THREE.Scenes]} input   Scene or Array of THREE.Scenes
@param  {Function} onDone  Callback on completed
@param  {Function} onError  Callback on errors
@param  {Object} options options