How can I group a sequence by two values and keep the order of the sequence?
<p>Let's say I have a list of Points.</p>

<pre><code>{(0,0), (0,0), (0,1), (0,0), (0,0), (0,0), (2,1), (4,1), (0,1), (0,1)}
</code></pre>

<p>How can I group this Points, so that all Points with the same x- and y-value are in one group, till the next element has other values?</p>

<p>The final sequence should look like this (a group of points is enclosed with brackets):</p>

<pre><code>{(0,0), (0,0)},
{(0,1)},
{(0,0), (0,0), (0,0)},
{(2,1)},
{(4,1)},
{(0,1), (0,1)}
</code></pre>

<p>Note that the order has to be exactly the same.</p>
