code: function serialize(obj) {
    if (!isObject(obj)) return obj;
    var pairs = [];
    for (var key in obj) {
      if (null != obj[key]) {
        pushEncodedKeyValuePair(pairs, key, obj[key]);
          }
        }
    return pairs.join('&');
  }
docs: Serialize the given `obj`.
  
  @param {Object} obj
  @return {String}
  @api private