How to use the dictdiffer.swap function in dictdiffer

def test_addition(self):
        result = 'add', '', [('a', 'b')]
        swapped = 'remove', '', [('a', 'b')]
        assert next(swap([result])) == swapped

        result = 'remove', 'a.b', [('c', 'd')]
        swapped = 'add', 'a.b', [('c', 'd')]
        assert next(swap([result])) == swapped

def test_changes(self):
        result = 'change', '', ('a', 'b')
        swapped = 'change', '', ('b', 'a')
        assert next(swap([result])) == swapped

patched = dict(current_joined)

        if patched["_version"] != target_version:
            for history_document in history_documents:
                entry_version = history_document["entry_version"]

                if entry_version == "removed" or entry_version >= target_version:
                    if history_document["method_name"] == "add":
                        patched = "remove"

                    elif history_document["method_name"] == "remove":
                        patched = history_document["changes"]
                        break

                    else:
                        diff = dictdiffer.swap(history_document["changes"])
                        patched = dictdiffer.patch(diff, patched)
                else:
                    break

        return patched

patched = deepcopy(current)

    # Sort the changes by descending timestamp.
    async for change in db.history.find({"kind.id": kind_id}, sort=[("created_at", -1)]):
        if change["kind"]["version"] == "removed" or change["kind"]["version"] > version:
            reverted_history_ids.append(change["_id"])

            if change["method_name"] == "remove":
                patched = change["diff"]

            elif change["method_name"] == "create":
                patched = None

            else:
                diff = dictdiffer.swap(change["diff"])
                patched = dictdiffer.patch(diff, patched)
        else:
            break

    if current == {}:
        current = None

    return current, patched, reverted_history_ids

patched = deepcopy(current)

    # Sort the changes by descending timestamp.
    for change in db.history.find({"otu.id": otu_id}, sort=[("otu.version", -1)]):
        if change["otu"]["version"] == "removed" or change["otu"]["version"] > version:
            reverted_history_ids.append(change["_id"])

            if change["method_name"] == "remove":
                patched = change["diff"]

            elif change["method_name"] == "create":
                patched = None

            else:
                diff = dictdiffer.swap(change["diff"])
                patched = dictdiffer.patch(diff, patched)
        else:
            break

    if current == {}:
        current = None

    return current, patched, reverted_history_ids

patched = deepcopy(current)

    # Sort the changes by descending timestamp.
    async for change in db.history.find({"virus.id": virus_id}, sort=[("created_at", -1)]):
        if change["virus"]["version"] == "removed" or change["virus"]["version"] > version:
            reverted_history_ids.append(change["_id"])

            if change["method_name"] == "remove":
                patched = change["diff"]

            elif change["method_name"] == "create":
                patched = None

            else:
                diff = dictdiffer.swap(change["diff"])
                patched = dictdiffer.patch(diff, patched)
        else:
            break

    if current == {}:
        current = None

    return current, patched, reverted_history_ids