Here's a good example IRL. https://github.com/vertexproject/synapse/blob/master/synapse/tools/backup.py#L56 https://github.com/vertexproject/synapse/blob/maste

Here's a good example IRL. https://github.com/vertexproject/synapse/blob/master/synapse/tools/backup.py#L56 https://github.com/vertexproject/synapse/blob/master/synapse... It grabs a transaction on an arbitrary number of databases, then yields.