emms-define-player not in sources

[Ergus]

Hi:

Recently I have started using emms, but I want to define my player
because mocp as a backend is much better from my point of view.

But looking in the documentation it reffers to emms-define-player but
that function doesn't exist in my sources at all.

Is this an error in the emms.info or I am missing something?

Best,
Ergus