code: function(options) {
        options= options || {};
  
        var self = this;
        if (!self._previousSave) {
          self._previousSave = self._source.then(function(base64, type) {
            var data = {
              base64: base64,
              _ContentType: type
            };
            return Parse._request({
              route: "files",
              className: self._name,
              method: 'POST',
              data: data,
              useMasterKey: options.useMasterKey
            });
  
          }).then(function(response) {
            self._name = response.name;
            self._url = response.url;
            return self;
          });
        }
        return self._previousSave._thenRunCallbacks(options);
      }
docs: Saves the file to the Parse cloud.
  @param {Object} options A Backbone-style options object.
  @return {Parse.Promise} Promise that is resolved when the save finishes.