I'd like to have a couple of secret keys available, like so

app.secret_keys = [
   'key-1',
   'key-2',
]

To allow them to rotate.

I've seen this issue which seems to have auto-closed
#1574

It seems like itsdangerous now supports this
pallets/itsdangerous#141

This would allow secret keys to be rotated regularly without sessions being invalidated.