/**
 * Provided a pattern or array of patterns, an input string, and an optional
 * mask character, returns a new string modified such that any tokens therein
 * matching one of the provided patterns is replaced by a string of mask
 * characters of the same length.
 *
 * @example
 *
 * mask(/foo/g, 'foo bar') // => '*** bar'
 */
export default function maskString(pattern: string | RegExp | Array<string | RegExp>, str: string, maskChar?: string): string;