[Zope] external method, not escaping < and >

Hi, I have an external method that fetches some web content (POP messages) then format an HTML output to make it easy to display. the Id of the external method is "mm". So as I said, it returns HTML content, with HTML tags and "<"s and ">"s. I directly call that external method from a ZPT this way: <div tal:content="python:here.mm()"> foo </div> the problem is the ">" and "<" returned by "mm" are all transformed to < and >. How to avoid that? Thank you.