import clr

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

clr.AddReference("RevitServices")
import RevitServices
from RevitServices.Persistence import DocumentManager
from RevitServices.Transactions import TransactionManager
from System.Collections.Generic import*

import System

uiapp = DocumentManager.Instance.CurrentUIApplication
app = uiapp.Application

docs = IN[0]
param_name = IN[1]
param_value = ""
param_list = []
names = []
param1 = None
result = []

for doc in docs:
	param_list = doc.FamilyManager.GetParameters()
	names = [p.Definition.Name for p in param_list]
	param_value = str(Document.DisplayUnitSystem.GetValue(doc))
	if param_name in names:
		param1 = param_list[names.index(param_name)]
	if param1 != None:
		TransactionManager.Instance.EnsureInTransaction(doc)
		try:
			doc.FamilyManager.Set(param1,param_value)
		except:
			pass
		TransactionManager.Instance.TransactionTaskDone()
	result.append(doc)
OUT = result