i know how hard it is to learn from scretch coding… 
in my snippets there are not the moduls included… you have to import them as well.
here the code in total!
# -*- coding: utf-8 -*-
__title__ = "IsolateTemporary"
__doc__ = """Date = 29.12.2023
_____________________________________________________________________
Description:
isolate Elements by selection
_____________________________________________________________________
Author: """
# IMPORTS
#==================================================
from Autodesk.Revit.DB import *
from Autodesk.Revit.DB.Architecture import *
from Autodesk.Revit.UI.Selection import ObjectType, PickBoxStyle, Selection
# pyrevit
from pyrevit import forms, revit, script, DB
# .NET Imports
import clr
clr.AddReference("System")
from System.Collections.Generic import List
uidoc = __revit__.ActiveUIDocument
doc = __revit__.ActiveUIDocument.Document
doc = __revit__.ActiveUIDocument.Document
uidoc = __revit__.ActiveUIDocument
selection = uidoc.Selection #type: Selection
isoView = doc.ActiveView
# 🛒 PickElemnetsbyRectangle
elements = selection.PickElementsByRectangle('Elements')
idlist = List[ElementId]()
for e in elements:
idlist.Add(e.Id)
# 🔓 🔒 Do some action in a Transaction
with revit.Transaction("isolate"):
if len(elements) > 0:
isoView.IsolateElementsTemporary(idlist)
