loadVMD( url, onLoad, onProgress, onError ) {

			const urls = Array.isArray( url ) ? url : [ url ];
			const vmds = [];
			const vmdNum = urls.length;

			const parser = this._getParser();

			this.loader.setMimeType( undefined ).setPath( this.animationPath ).setResponseType( 'arraybuffer' ).setRequestHeader( this.requestHeader ).setWithCredentials( this.withCredentials );

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

				this.loader.load( urls[ i ], function ( buffer ) {

					vmds.push( parser.parseVmd( buffer, true ) );
					if ( vmds.length === vmdNum ) onLoad( parser.mergeVmds( vmds ) );

				}, onProgress, onError );

			}

		}
Loads .vmd file as an Object. If two or more files are specified
they'll be merged.

@param {string|Array<string>} url - url(s) to .vmd file(s)
@param {function} onLoad
@param {function} onProgress
@param {function} onError