Because without the map(None + ....), your last row will be short
elements if it doesn't divide pefectly.
So, if you're cols was 3, you'd get:
[(1,2,3), (4,)]
and of course, that could create bad html:
<table>
<tr>
<td>1</td>
<td>2</td>
<td>3</td>
</tr>
<tr>
<td>4</td>
</tr>
</table>
So, now with the Map, the left over cells are set to None, so that's
why the template does the {% if cell %} test inside the <TD> tag so you
can have some empty cells finish off the row:
eg:
<tr>
<td>4</td>
<td></td>
<td></td>
</tr>......
You're right about the list of tuples instead of list of lists, but I
only ever need iterables...
