Feature request: support signal values

[theSherwood]

I've got a use case in which I want to store signals as values in an in-memory tuple db. As functions, they aren't a valid value type. I get that this would break isomorphism with durable tuple db instances, but is loosening that restriction on in-memory db instances something you would consider?

[theSherwood]

Seems you already support this! My bad!