Umm, is that crawly thing the plumbing vent?

Old houses never cease to amaze me. There is a charming Delaware Craftsman style house I previewed recently to see if I could give the owner any advice about getting the home ready for sale. Always ready to plunge into dark places, I popped  my head into the attic, and this is what I saw. 

The owner had no idea what the thing that looks like dryer vent pipe was, and wasn't sure what the fan thing in the wall was.  He has since gotten back to me and said the snakey pipe thing was a plumbing vent, and the fan was a thermostatically controlled attic vent. So his assignment is now to find out what the plumbing code says about vents (3 guesses, first 2 don't count), and where the control is for the fan (he is removing the plastic cover from it).  I'm not a plumber, but this snakey thing is definitely fishy (I know, mixed metaphor). 

Older houses are my thing, give me a ring.

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