@spectrum-web-components/base/src/define-element.d.ts

The `SpectrumElement` base class as created by mixing `SpectrumMixin` onto `LitElement` adopts `dir` values from the `document` at connection time with a fallback to `lrt`. In a TypeScript context, it also enforces the presence of `this.shadowRoot` on ext

interface CustomElementConstructor {
    new (...params: unknown[]): HTMLElement;
}
export declare function defineElement(name: string, constructor: CustomElementConstructor): void;
export {};