code: function sortTransactions(allTransactions, callback) {
      allTransactions.push(notificationDetails.transaction);
  
      var txns = _.uniq(allTransactions, function(tx) {
        return tx.hash;
      });
  
      txns.sort(utils.compareTransactions);
  
      callback(null, txns);
    }
docs: Sort the transactions returned by ledger_index and remove duplicates