Host railing to topo

RailingToTopo.py

import clr
clr.AddReference('RevitAPI')
from Autodesk.Revit.DB import *
clr.AddReference('RevitServices')
import RevitServices
from RevitServices.Persistence import DocumentManager
from RevitServices.Transactions import TransactionManager

doc = DocumentManager.Instance.CurrentDBDocument

railings = UnwrapElement(IN[0])
newHost = UnwrapElement(IN[1])

TransactionManager.Instance.EnsureInTransaction(doc)
# in a for loop, i represents an instance of the object in a list. 
# so it can be looked at as "for each railing (i) in railings"      
for i in railings:
  i.HostId = newHost.Id # we get the id in here for simplicity
TransactionManager.Instance.TransactionTaskDone()

OUT = railings