doc:   [
    DocGroup({"tag": "bullet"}, [
        DocGroup({"tag": "h2"}, [
            DocChars("1"),
        ]),
        DocGroup({"tag": "h2"}, [
            DocChars("1"),
        ]),
    ]),
]

a_del: [
    DelWithGroup([
        DelGroup([
            DelSkip(1),
        ]),
        DelWithGroup([
            DelSkip(1),
        ]),
    ]),
]
a_add: [
    AddWithGroup([
        AddGroup({"tag": "pre"}, [
            AddChars("L"), AddGroup({"tag": "caret", "client": "e"}, []),
            AddChars(" "), AddSkip(1), AddGroup({"tag": "caret", "client": "d"}, []),
            AddChars(" "), AddGroup({"client": "c", "tag": "caret"}, []),
            AddGroup({"client": "f", "tag": "caret"}, []),
        ]),
        AddWithGroup([
            AddGroup({"client": "a", "tag": "caret"}, []),
            AddSkip(1),
        ]),
    ]),
]

b_del: [
    DelWithGroup([
        DelWithGroup([
            DelSkip(1),
        ]),
        DelGroup([
            DelChars(1)
        ])
    ])
]
b_add: [
    AddWithGroup([
        AddWithGroup([
            AddSkip(1),
        ]),
        AddGroup({"tag": "h2"}, [
            AddChars(" "),
            AddGroup({"tag": "caret", "client": "h"}, [])
        ])
    ])
]