how to use a list with strm files in ?

hi guys, your expertise is needed again. I need some help.

I have a python list with a bunch of video strm files from Disney/Netflix/Amazon.

In my py file I use

py:
import xbmc

import xbmcgui



xbmcgui.Window(id).setProperty( 'ShowStrms' ,  customstrms)

and in my list container I add the <content> tag just before <itemlayout> like so:

xml:
<content>$INFO[Window(id).Property(ShowStrms)]</content>

Kodi log gives me an error:  TypeError: argument "value" for method "setProperty" must be unicode or str.

Ok, so it does not accept a python list. Now the question:

Is there a way to convert my list so Kodi can read my strm files? 

I appreciate any help!