What is the simplest way of doing @nogc string concatenation?

[Steven Schveighoffer via Digitalmars-d-learn]

On 11/3/16 2:54 PM, Gary Willoughby wrote:
> What is the simplest way of doing @nogc string concatenation?

Where does it go?

For instance, this should work:

auto newstr = "hello, ".chain("world");

-Steve