I do not see the use for this, over the standard access methods.

    people = {
        "Diane": 70,
        "Bob": 78,
        "Emma": 84
    }

    people.get("Bob")
    # 78

The common usecase is:

    for key in people.keys():
        people.get(key)

vs

    keys = people.keys()
    # dict_keys(['Diane', 'Bob', 'Emma'])

    for key in keys:
        keys.mapping[key]

What is the advantage?