function formatArray(array, options) {
  if (Array.isArray(array)) {
    var str = '[';
    var len = array.length;

    for (var i = 0; i < len; i++) {
      if (i !== 0) {
        str += ', ';
      }

      str += formatArray(array[i], options);
    }

    str += ']';
    return str;
  } else {
    return exports.format(array, options);
  }
}
Recursively format an n-dimensional matrix
Example output: "[[1, 2], [3, 4]]"
@param {Array} array
@param {Object | number | Function} [options]  Formatting options. See
                                               lib/utils/number:format for a
                                               description of the available
                                               options.
@returns {string} str