Python help - Get subelements

@SeanP

This post talks about a bit about how I got to this point. I am bascially automatting stair documentation. So take a stair(s), get its risers/landing and create dimension, tags, number systems, etc. It is all working except for if it is a multistorey stair. I need to be able to get the typology of each substair.

I tried with both Id and UniqueId and both returned the error: AttributeError: ‘list’ object has no attribute ‘UniqueId’

"
import clr

clr.AddReference('RevitServices')
import RevitServices
from RevitServices.Persistence import DocumentManager
from RevitServices.Transactions import TransactionManager
doc = DocumentManager.Instance.CurrentDBDocument

clr.AddReference('RevitNodes')
import Revit
clr.ImportExtensions(Revit.Elements)
clr.ImportExtensions(Revit.GeometryConversion)

clr.AddReference('RevitAPI')
from Autodesk.Revit.DB import *

str1 = []
str2 = []
str3 = []
mstr = UnwrapElement(IN[0])
stid = mstr.GetAllStairsIds()
for i in stid:
str1.append(doc.GetElement(i))
for s in str1:
str2.append(s.GetSubelements())
for t in str2:
str3.append(str2.UniqueId)

OUT = str3, str2, str1, stid
";