I m trying to create a list like i use in python but after creating it here i m not able to add more items in it, when i use checkNumber.append(3) its say error that " append is not a member of Boo.Lang.List" PLZ HELP

import UnityEngine

class book (MonoBehaviour):

def Update():
    if Input.GetButtonDown('Fire1'):
        insert()

def insert():
    checkNumber = [0,1,2,3]           //is a list
              checkNumber.append(4)             //adding more no.