'auto' with AA

[David Held via Digitalmars-d-learn]

I would like to do something like this:

Foo[Bar][Baz] nestedAA;
auto innerAA = nestedAA[someBaz];
innerAA[someBar] = someFoo;
assert(someFoo in nestedAA[someBaz]);
Unfortunately, this does not do what I would like, because innerAA 
appears to be a copy rather than a reference.  Is there a nice way to 
tell 'auto' that I want a reference instead?

Dave