Is there any way to initialize a Sequential value *not* in one fellow swoop?

Like, can I declare it, then use a for loop to populate it, step by step?

As this could all happen inside a class body, the true immutability of the Sequential value could then kick in once the class instance construction phase has been completed.

Example:

```
Sequential<String> strSeq;

for (i in span(0,10)) {
    strSeq[i] = "hello";
}

```

This code doesn't work, as I get this error:

> 
> Error:(12, 9) ceylon: illegal receiving type for index expression:
>  'Sequential' is not a subtype of 'KeyedCorrespondenceMutator' or
>  'IndexedCorrespondenceMutator'
> 
> 
> 

So what I can conclude is that sequences *must* be assigned in *one* statement, right?