how to expand tuple?

[Suliman via Digitalmars-d-learn]

Few questions.

1. In examples tuples are created with keyword auto. Can I create 
them with another keyword. Or auto mean structure of data, that 
have not standard type like (int or string)?

2. How ti expend tuple? I tried to do:

    auto imglist = tuple("aaa");
    imglist.expand["sss"];
    writeln(imglist);

but got very strange error:
app.d(30): Error: cannot implicitly convert expression ("sss") of 
type string to  uint