Get by filter

from Autodesk.Revit.DB import *
uidoc = __revit__.ActiveUIDocument
doc = uidoc.Document
import System
from System import Array
from System.Collections.Generic import *

try:
    cat_list = [BuiltInCategory.OST_Walls, BuiltInCategory.OST_Windows, BuiltInCategory.OST_Doors]
    typed_list = List[BuiltInCategory](cat_list)
    filter = ElementMulticategoryFilter(typed_list)
    output = FilteredElementCollector(doc).WherePasses(filter).ToElements()

for i in output:
    print i