Python 3.9 is now generally available.

google.appengine.datastore.datastore_rpc.TransactionMode

The mode of a Datastore transaction.

Inherits From: expected_type

Specifying the mode of the transaction can help to improve throughput, as it provides additional information about the intent (or lack of intent, in the case of a read only transaction) to perform a write as part of the transaction.

READ_ONLY 1
READ_WRITE 2
UNKNOWN 0