How to resume iteration from previous point in associative array

[Tarman]

I guess what might work here is to allow some kind of argument to 
"byKey" that will let us resume so maybe something like:

foreach (item; 
massiveAssociativeArray.byKey(indexOfKeyToStartFrom)) {
}

If something like this isn't possible, then would one of our 
engineers be able to submit a patch to libphobos to provide the 
feature?