regex, preg_replace: replacing multiple instances with single
===

I have auto generated string.

One of its elements is a group "/__nh".

Sometimes it is being multiplied, e.g.:

<pre>
$string = some_stuff_here/__nh/__nh/__nh
</pre>

I tried code below (and some other variation as well) to replace replace multiple instances with a single one:

<pre>
return preg_replace('/(//__nh)+/', '/__nh', $string);
</pre>

.. but I failed (regex is not something I'm comfortable with).
