parse( input, onDone, options ) {

			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 );

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