found in cloud-init documentation. If no mergers
    have been specified, entries will be recursively added, but no values
    get replaced if they already exist. Functionally, this means that the
    highest priority keys must be specified first.

    Example:
    a = {
        "a": 1,
        "b": 2,
        "c": [1, 2, 3],
        "d": {
            "a": 1,
            "b": 2,
        },
    }

    b = {
        "a": 10,
        "c": [4],
        "d": {
            "a": 3,
            "f": 10,
        },
        "e": 20,
    }

    mergemanydict([a, b]) results in:
    {
        'a': 1,
        'b': 2,
        'c': [1, 2, 3],
        'd': {
            'a': 1,
            'b': 2,
            'f': 10,
        },
        'e': 20,
    }
    )