[rakoo]

The relevant part of Effective Go is here: http://golang.org/doc/effective_go.html#blank_implements

It allows you to make sure fancyWriter implements all those interfaces, so that any future refactoring that breaks compatibility breaks at compile time.

You know how Go makes interfaces concordance implicit ? Whatever has a Read() method is a io.Reader without asking for it ? This explicitly tells the compiler (and other developers) the same thing.

[Sphax]

Thank you, I read the wrong part of effective Go apparently, didn't see this. It's clear now.