[Zope] Month number as string as variable

[peter be]

Dear All.

What I want to do is display this months Poll.
I have created three Polls ( from the Poll Product ), named month_06, month_07, month_08.
I understand that I will have to use the getitem() function to "show" the Poll itself, but I don't know how to create the string "month_0X"

<dtml-var "ZopeTime()" fmt="%m"> ...returns (today) '08' Good!

<dtml-let monthnr="ZopeTime()">
    <dtml-var monthnr fmt="%m"> ...also returns (today) '08' Good!
</dtml-let>

But I don't want to use the fmt when I display it. 
I'd like to have something like this:
<dtml-let monthnr=("ZopeTime()" fmt="%m")>        * this is where the problem lies.
    <dtml-let monthPoll="'month_'+monthnr">
    <dtml-var "_.getitem(monthPoll)">
</dtml-let>
But this obviously, is bad syntax.
(I have tried [] squared brackets as well)

Best Regards, Peter