Undefined CreateImmutableBinding(N:String)
Create an uninitialized immutable Binding. You must initialize this Binding before you can get a value from it. Once set, you can't change it (duh).
In these examples, a Binding is an object {value:mixed, mutable:Boolean, deletable:Boolean, initialized:Boolean}
function CreateImmutableBinding(N){
var envRec = this;
if (N in envRec) return; // "assert" N doesn't already exist.
envRec[N] = {value:undefined, mutable:false, deletable:true, initialized:false};
}