[Tex/LaTex] How to draw a surjective (double-headed) arrow between two nodes in TikZ

Question

I can't find how to draw a surjective arrow between two nodes in TikZ.
I'd like it to look somewhat like this.

Answer 1

A pure TikZ solution involves using ->> and that's about it:

\documentclass{article} 
\usepackage{tikz} 
\begin{document}
\begin{tikzpicture} 
\node at (0,0) (a) {A};
\node at (1,0) (b) {B};
\path [draw,->>] (a) -- (b);
\end{tikzpicture}
\end{document}

And we are done. :)