code: function arrayToRegexp(arr, keys, options) {
    let parts = [];
    arr.forEach(ele => parts.push(toRegexpSource(ele, keys, options)));
    return new RegExp(`(?:${parts.join('|')})`, flags(options));
  }
docs: Transform an array into a regular expression.
  
  @param  {!Array}  arr
  @param  {Array=}  keys
  @param  {Object=} options
  @return {!RegExp}