A Collab with children may store the children's save data in children;
this is usually more convenient than serializing everything
into a single Uint8Array.
The return value of Collab.save is normalized before being passed to
Collab.load:
If self was undefined, it is replaced by an empty Uint8Array.
If children was undefined, it is replaced by an empty Map.
Optimized representation of saved state used by Collab.save and Collab.load.
A Collab with children may store the children's save data in children; this is usually more convenient than serializing everything into a single Uint8Array.
The return value of Collab.save is normalized before being passed to Collab.load: