/**
 * Used in unit test.
 * @ignore
 */
export declare function calcBackoffMs(attempt: number): number;
/**
 * Recursively delete directory contents.
 *
 * This is used when cleaning the `distDir`, and is part of the critical path
 * for starting the server, so we use synchronous file IO, as we're always
 * blocked on it anyways.
 *
 * Despite using sync IO, the function signature is still `async` because we
 * asynchronously perform retries.
 */
export declare function recursiveDeleteSyncWithAsyncRetries(
/** Directory to delete the contents of */
dir: string, 
/** Exclude based on relative file path */
exclude?: RegExp, 
/** Relative path to the directory being deleted, used for exclude */
previousPath?: string): Promise<void>;