text: 'use strict';
  
  var debug;
  if (process.env.NODE_ENV !== 'production') {
      debug = require('debug')('hbnb:module:flight:selectCity');
  }
  
  var _invoke = require('../invoke');
  
  /**
   * 选择城市
   *
   * @memberof flight
   * @static
   * @name selectCity
   * @param {String} city
   * @return {Promise}
   * @example
   *  hbnb.flight.selectCity('city')
   *      .then(function(city) {
   *          city = {
   *              cityName: '',
   *              cityPinyin: ''
   *          }
   *      });
   */
  module.exports = function(city) {
      if (process.env.NODE_ENV !== 'production') {
          debug('city is %s', city);
      }
      city = city || '';
  
      var p = new Promise(function(resolve, reject) {
          _invoke('flight', 'select_city', {
              original: city,
              callback: function(city) {
                  resolve(city);
              }
          });
      });
      return p;
  };
  