private Namespace getNamespace(FunctionNode root, FunctionNodeContainer container) {
		Function function =
			container.getProgram().getFunctionManager().getFunctionAt(root.getAddress());
		if (function == null) {
			return null;
		}
		Namespace namespace = function.getParentNamespace();
		return namespace;
	}
A neighborhood generator that, for a given function, generates all functions
in the same namespace.  For efficiency, it caches the namespace sets it generates.
Ghidra/Features/VersionTrackingBSim/src/main/java/ghidra/feature/vt/api/NamespaceNeighborhood.java