/**
 * Basic string formatting, akin to `sprintf` or `util.format`, but limited.
 * Only supports `%o` for arrays, `%j` for objects, `%s` for strings and `%d` for numbers.
 *
 * You should really be using template literals instead (developer's note to self, lol).
 * @param fmt Input
 * @param args Arguments
 * @returns Formatted string
 */
export declare function formatstr(fmt: string, ...args: any[]): string;