Hi Mustapha,
You need to import the System collection in RevitServices to use ICollection (ICollection)
You will find an example below :
clr.AddReference('RevitNodes')
import Revit
clr.ImportExtensions(Revit.Elements)
clr.AddReference('RevitServices')
import RevitServices
from RevitServices.Persistence import DocumentManager
from System.Collections.Generic import *
clr.AddReference('RevitAPI')
import Autodesk
from Autodesk.Revit.DB import *
elements = UnwrapElement(IN[0])
select = []
for i in elements:
select.append(i.Id)
Icollection = List[ElementId](select)
DocumentManager.Instance.CurrentUIApplication.ActiveUIDocument.Selection.SetElementIds(Icollection)
OUT = elements