doc:   [
    DocGroup({"tag": "h1"}, [
        DocGroup({"tag": "caret", "client": "a"}, []),
        DocChars(" "), DocGroup({"client": "b", "tag": "caret"}, []),
        DocChars(" "), DocGroup({"client": "c", "tag": "caret"}, []),
        DocChars("B7Hello worldl")
    ]),
    DocGroup({"tag": "h1"}, [
        DocChars("W"), DocGroup({"client": "d", "tag": "caret"}, []),
        DocChars("hat\'s up with you?")
    ])
]

a_del: [
    DelGroup([
        DelGroup([]),
        DelSkip(1), DelGroup([]),
        DelSkip(1), DelGroup([]),
        DelChars(1), DelSkip(13)
    ]),
    DelGroup([
        DelSkip(20)
    ])
]
a_add: [
    AddGroup({"tag": "bullet"}, [
        AddGroup({"tag": "h1"}, [
            AddGroup({"client": "a", "tag": "caret"}, []),
            AddChars("S h"), AddSkip(1), AddChars("2"), AddSkip(1), AddGroup({"tag": "caret", "client": "c"}, []),
            AddChars("v"), AddSkip(13), AddGroup({"client": "b", "tag": "caret"}, [])
        ])
    ]),
    AddGroup({"tag": "h1"}, [
        AddSkip(20)
    ])
]

b_del: [
    DelWithGroup([
        DelWithGroup([]),
        DelSkip(1), DelWithGroup([]),
        DelSkip(1), DelWithGroup([]),
        DelSkip(14)
    ]),
    DelWithGroup([
        DelChars(1), DelGroup([]),
        DelChars(2)
    ])
]
b_add: [
    AddWithGroup([
        AddWithGroup([]),
        AddSkip(1), AddWithGroup([]),
        AddSkip(1), AddWithGroup([]),
        AddSkip(14)
    ]),
    AddWithGroup([
        AddChars("a"), AddGroup({"client": "d", "tag": "caret"}, []),
        AddChars(" ")
    ])
]