your ${adjective} template here
`;\n * }\n * }\n *\n * customElements.define('my-element', MyElement);\n * ```\n *\n * `LitElement` extends [[`UpdatingElement`]] and adds lit-html templating.\n * The `UpdatingElement` class is provided for users that want to build\n * their own custom element base classes that don't use lit-html.\n *\n * @packageDocumentation\n */\n\n\n\n\n\n\n\n// IMPORTANT: do not change the property name or the assignment expression.\n// This line will be used in regexes to search for LitElement usage.\n// TODO(justinfagnani): inject version number at build time\n(window['litElementVersions'] || (window['litElementVersions'] = []))\n .push('2.4.0');\n/**\n * Sentinal value used to avoid calling lit-html's render function when\n * subclasses do not implement `render`\n */\nconst renderNotImplemented = {};\n/**\n * Base element class that manages element properties and attributes, and\n * renders a lit-html template.\n *\n * To define a component, subclass `LitElement` and implement a\n * `render` method to provide the component's template. Define properties\n * using the [[`properties`]] property or the [[`property`]] decorator.\n */\nclass LitElement extends _lib_updating_element_js__WEBPACK_IMPORTED_MODULE_1__[\"UpdatingElement\"] {\n /**\n * Return the array of styles to apply to the element.\n * Override this method to integrate into a style management system.\n *\n * @nocollapse\n */\n static getStyles() {\n return this.styles;\n }\n /** @nocollapse */\n static _getUniqueStyles() {\n // Only gather styles once per class\n if (this.hasOwnProperty(JSCompiler_renameProperty('_styles', this))) {\n return;\n }\n // Take care not to call `this.getStyles()` multiple times since this\n // generates new CSSResults each time.\n // TODO(sorvell): Since we do not cache CSSResults by input, any\n // shared styles will generate new stylesheet objects, which is wasteful.\n // This should be addressed when a browser ships constructable\n // stylesheets.\n const userStyles = this.getStyles();\n if (Array.isArray(userStyles)) {\n // De-duplicate styles preserving the _last_ instance in the set.\n // This is a performance optimization to avoid duplicated styles that can\n // occur especially when composing via subclassing.\n // The last item is kept to try to preserve the cascade order with the\n // assumption that it's most important that last added styles override\n // previous styles.\n const addStyles = (styles, set) => styles.reduceRight((set, s) => \n // Note: On IE set.add() does not return the set\n Array.isArray(s) ? addStyles(s, set) : (set.add(s), set), set);\n // Array.from does not work on Set in IE, otherwise return\n // Array.from(addStyles(userStyles, new Set