Failing Pregel Doctest (#332)

* Failing doctest

* Changing the order of examples

Author: apetenchea

docs/pregel.rst

@@ -12,7 +12,7 @@ iterative graph processing. For more information, refer to `ArangoDB manual`_.
 
 **Example:**
 
-.. testcode::
+.. code-block:: python
 
     from arango import ArangoClient
 

docs/transaction.rst

@@ -68,6 +68,13 @@ logical unit of work (ACID compliant).
     assert '_rev' in txn_col.insert({'_key': 'Lily'})
     assert len(txn_col) == 6
 
+    # Abort the transaction
+    txn_db.abort_transaction()
+    assert 'Kate' not in col
+    assert 'Mike' not in col
+    assert 'Lily' not in col
+    assert len(col) == 3  # transaction is aborted so txn_col cannot be used
+
     # Fetch an existing transaction. Useful if you have received a Transaction ID
     # from some other part of your system or an external system.
     original_txn = db.begin_transaction(write='students')
@@ -76,13 +83,7 @@ logical unit of work (ACID compliant).
     txn_db = db.fetch_transaction(original_txn.transaction_id)
     txn_col = txn_db.collection('students')
     assert '_rev' in txn_col.insert({'_key': 'Alya'})
-
-    # Abort the transaction
     txn_db.abort_transaction()
-    assert 'Kate' not in col
-    assert 'Mike' not in col
-    assert 'Lily' not in col
-    assert len(col) == 3  # transaction is aborted so txn_col cannot be used
 
 See :ref:`TransactionDatabase` for API specification.