FullyQualifiedNamespace
A fully qualified namespace includes the interpreter's own namespacing logic
IN ADDITION to the calling contract's requested StateNamespace. Typically
this involves hashing the msg.sender into the StateNamespace so that each
caller operates within its own disjoint state universe. Intepreters MUST NOT
allow either the caller nor any expression/word to modify this directly on
pain of potential key collisions on writes to the interpreter's own storage.
type FullyQualifiedNamespace is uint256;