docs: function executeSaveLoad(that, method, file, cb, options) {
          var ff, format;
          validateSaveLoadParameters(that, method, file, cb, options);
          if (!that.storageAvailable()) {
              that.throwErr('Error', 'save', 'no persistent storage available');
          }
          options = options || {};
          format = extractExtension(file);
          // If try to get the format function based on the extension,
          // otherwise try to use the default one. Throws errors.
          ff = findFormatFunction(that, method, format);
          ff(that, file, cb, options);
      }