原型模式深拷贝

def solve():
    import copy
    class Document:
        def __init__(____):
            self.title = title
            self.tags = tags
        def deep_clone(____):
            return copy.deepcopy(____)
    doc1 = Document(____)
    doc2 = doc1.deep_clone()
    doc2.tags.append(____)
    print(____)