function formatArray (k, v) {
    if (_.isString(v)) { return v; }
    if (_.isNumber(v)) {
      var s = formatNumber(v);
      return new Array(Math.max(0, nChars - s.length + 2)).join(' ') + s;
    }
    k = k || 0;
    var arr;
    var th = CONF.printThreshold;
    var hth = th / 2 | 0;
    if (v.length > th) {
      arr = [].concat(v.slice(0, hth), [' ...'], v.slice(v.length - hth));
    } else {
      arr = v;
    }
    return new Array(k + 1).join(' ') + '[' + arr.map(function (i, ii) {
      return formatArray(ii === 0 && k === 0 ? 1 : k + 1, i);
    }).join(',') + ']';
  }
Stringify the array to make it readable by a human.

@returns {string}