Pretty Printing TickDuration

[Nordlöw via Digitalmars-d-learn]

Currently

     import std.datetime: StopWatch;
     StopWatch sw;
     sw.start;
     writeln(sw.peek());

prints for instance

     TickDuration(279483)

I've seen Phobos doing something much more clever such as pretty 
printing of time in the format:

1 hour, 2 seconds, 3 milliseconds, etc.

How do I convert an instance of `TickDuration` to that format?