code: function normalizeProperties(properties) {
    return _.map(properties, function(val) {
      if(_.isString(val)) {
        return [val, false];
      } else if(val.length === 2){
        return [val[0], val[1].toLowerCase() === "desc"];
      } else {
        throw new Error("Wrong format for index definition, ['property name', 'desc'|'asc'] required");
      }
    });
  }
docs: Each property must be in the form:
  ['propertyName', true | false]
  
  false is ASC (default)
  true is DESC