extensions of Snapshot signature

[nancyday]

In Dash models the snapshot is an extension of another snapshot as in:

open util/steps[Snapshot]

// Snapshot definition
sig Snapshot extends BaseSnapshot {
stable: one Bool,
Mutex_semaphore_free : one Bool
}

There are snapshot elements in BaseSnapshot that we would like to see in the ALDB output. Is it possible to collect all Snapshot elements back through the inheritance hierarchy?