If I passed a list of key ids as an argument in a transaction, would the change associated with the first key in the list happen first? And if not, how do I specify the order that I want the changes to happen in?

As a concrete example, consider this code below from Google Docs Transactions--would changes to the first item in acc.key() happen first?

class Accumulator(db.Model):
    counter = db.IntegerProperty()

Docshttp://code.google.com/appengine/docs/python/datastore/transactions.html:
def increment_counter(key, amount):
    obj = db.get(key)
    obj.counter += amount
    obj.put()

q = db.GqlQuery("SELECT * FROM Accumulator")
acc = q.get()
db.run_in_transaction(increment_counter, acc.key(), 5)