constructor( hotkeys, alias ) {
		super();
		// make sure that we've always got two hotkeys
		if ( hotkeys.length !== 2 ) {
			hotkeys.push( undefined, undefined );
			hotkeys.splice( 2 );
		}
		this.push( ...hotkeys.map( h => new Hotkey( h ) ) );
		this.alias = alias;
	}
@param {Hotkey[]} hotkeys
@param {string?} alias