An interface must be a small as possible to fulfill it's purpose, no smaller and no larger. It's not about implementation, it's about the mental model of what i

An interface must be a small as possible to fulfill it's purpose, no smaller and no larger. It's not about implementation, it's about the mental model of what is expected and why. Another way to say this is that an interface must be perfectly sized, but perhaps that is to abstract to be useful. Rob Pike mentioned few methods because that is the only thing that interfaces mean in Go - he might have used different terminology in another context or speaking about abstraction of systems instead of interfaces alone as abstractions.