update code examples

Author: stephmarie17

source/examples/generated/TransactionsTest.snippet.transaction.kt

@@ -1,7 +1,8 @@
 // Set up the MongoDB client and get the collection
 suspend fun performTransaction(client: MongoClient) {
     client.startSession().use { session ->
-        session.startTransaction() // Start the transaction
+        // Start the transaction
+        session.startTransaction()
         try {
             val database = client.getDatabase("bank")
 
@@ -18,6 +19,7 @@ suspend fun performTransaction(client: MongoClient) {
                 CheckingAccount::accountId eq "9876",
                 inc(CheckingAccount::amount, 100)
             )
+
             // Commit the transaction
             session.commitTransaction()
             println("Transaction committed.")
@@ -28,12 +30,3 @@ suspend fun performTransaction(client: MongoClient) {
         }
     }
 }
-
-data class SavingsAccount(val accountId: String, val amount: Int)
-data class CheckingAccount(val accountId: String, val amount: Int)
-
-fun main() = runBlocking {
-    val uri = "<connection string uri>"
-    val client = MongoClient.create(uri)
-    performTransaction(client)
-}

source/fundamentals/transactions.txt

@@ -96,6 +96,13 @@ and commit a changes to existing documents:
 #. Update the specified documents, then use the ``commitTransaction()`` method if all
    operations succeed, or ``abortTransaction()`` if any operations fail.
 
+This example uses the following {+language+} data classes to model its documents:
+
+.. code-block:: kotlin
+
+    data class SavingsAccount(val accountId: String, val amount: Int)
+    data class CheckingAccount(val accountId: String, val amount: Int)
+
 .. literalinclude:: /examples/generated/TransactionsTest.snippet.transaction.kt
    :language: kotlin
    :copyable: