code: function filterAttributes(obj) {
      var attribute;
      for (attribute in obj) {
          if (obj.hasOwnProperty(attribute)) {
              if (obj[attribute] === undefined || obj[attribute] === null) {
                  delete obj[attribute];
              } else if (lodash.isString(obj[attribute])) {
                  obj[attribute] = obj[attribute].quote();    // DO NOT quote type string. It is a JS variable.
              }
          }
      }
      return obj;
  }
docs: Given plain object, this function does the following:
  - Strips null or undefined values from object,
  - Add quotes around string values
  @private
  @param {object} obj - Simple object to filter.
  @returns {object}