docs: function formatsToJSON(attrs, options) {
          var defaultFormats = ['html'],
              formatsToKeep = options.formats || defaultFormats;
  
          // Iterate over all known formats, and if they are not in the keep list, remove them
          _.each(Post.allowedFormats, function (format) {
              if (formatsToKeep.indexOf(format) === -1) {
                  delete attrs[format];
              }
          });
  
          return attrs;
      }