class Start:
    def __init__(self):
        self.mylist = []

    def run(self):
        foo(self.mylist)
        print(self.mylist)

def foo(listRef):
    bar(listRef)

def bar(listRef):
    someItem = "Hello, World!"
    put_item(listRef, someItem)

def put_item(listRef, obj):
    listRef.append(obj)

x = Start()
x.run()