Undefined InitializeImmutableBinding(N:String, V:mixed)
Initialize a fresh uninitialized immutable Binding to V. This can only be done once per immutable Binding (what else did ya expect).
In these examples, a Binding is an object {value:mixed, mutable:Boolean, deletable:Boolean, initialized:Boolean}
function InitializeImmutableBinding(N, V){
var envRec = this;
if (!(N in envRec) || !envRec[N].immutable || envRec[N].initialized) return; // "assert" N exists, is immutable and uninitialized
envRec[N].value = V;
envRec[N].initialized = true;
}