[ZPT] I don't want "&" to be URL escaped in tal:attributes, how to do?

[iap@y2fun.com]

Hi, all
I want to render a URL by tal:attributes:
<a href="" tal:attributes="href python:
here.absolute_url()+'?var1=A&var2=B'">
the & in '?var1=A&var2=B' will be "escaped" to &amp;
That make unexpected URL to be generated,
How to keep "&" to be "&" not "&amp;"

Thanks

Iap, Singuan