/**
 * Normalizes email so that equivalent emails can be compared.
 */
export declare function normalizeEmail(email: string): string;
/**
 * Returns whether or not the parameter is an email address.
 */
export declare function validateEmail(email: string): boolean;
/**
 * Converts `{ a: { b: "c" }, d: "e", f: { } }`
 * Into:
 * ```
 * [
 *   ["a.b": "c"],
 *   ["d": "3"]
 * ]
 * ```
 */
export declare function flattenObject(obj: object | undefined): Array<[string, string]>;
/**
 * Shorthand for {@code JSON.stringify}
 */
export declare function str(val: unknown): string;
/**
 * Formats a duration of milliseconds into hh:mm:ss.
 */
export declare function fmtDuration(totalMs: number): string;
/**
 * Converts an empty string to undefined, while passing other argument
 * values through unmodified.
 */
export declare function emptyStrToUndefined(inStr: string | undefined): string | undefined;
export declare function tryParse<T>(str: unknown): T | undefined;
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