@argument {Object} options - Modifiers configuration and options\n * @returns {Object} The data object, properly modified\n */\nexport default function arrow(data, options) {\n  // arrow depends on keepTogether in order to work\n  if (!isModifierRequired(data.instance.modifiers, 'arrow', 'keepTogether')) {\n    return data;\n  }\n\n  let arrowElement = options.element;\n\n  // if arrowElement is a string, suppose it's a CSS selector\n  if (typeof arrowElement === 'string') {\n    arrowElement = ...