Problem Flattening List With Design Script

I thought your workaround sounded quite straightforward but when I was working through it today I got the unexpected error “closeparen expected”. Searching online it looks like this is almost certainly 100% user error but I couldn’t find my mistake. Could this be a bug in Dynamo 2.0.2? In any case, I must avail myself to the forums again for help.

The reason I’m trying to write a script that segments exterior wall geometry by level is because I don’t necessarily want to segment and post-process each exterior building wall the same. The post-processing I want to try on each surface is trivial assuming I can actually get the list into a usable configuration. I’m trying to achieve a flat 1 level deep list as output .

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