code: function (obj, encode) {
          if (!obj) { return EMPTY; }
  
          var key = obj.key,
              value = obj.value;
  
          if (value === undefined) {
              return EMPTY;
          }
  
          if (key === null) {
              key = EMPTY;
          }
  
          if (value === null) {
              return encode ? urlEncoder.encode(key) : key;
          }
  
          if (encode) {
              key = urlEncoder.encode(key);
              value = urlEncoder.encode(value);
          }
  
          return key + EQUALS + value;
      }
docs: Takes a query param and converts to string
  
  @param {Object} obj
  @param {Boolean} encode
  @returns {String}
  
  @deprecated since v3.4.6, drop support for `encode`