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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get(msg_or_dict, key, default=_SENTINEL):
 """Retrieve a key's value from a protobuf Message or dictionary. Args: mdg_or_dict (Union[~google.protobuf.message.Message, Mapping]):
 the object. key (str):
 The key to retrieve from the object. default (Any):
 If the key is not present on the object, and a default is set, returns that default instead. A type-appropriate falsy default is generally recommended, as protobuf messages almost always have default values for unset values and it is not always possible to tell the difference between a falsy value and an unset one. If no default is set then :class:`KeyError` will be raised if the key is not present in the object. Returns: Any: The return value from the underlying Message or dict. Raises: KeyError: If the key is not found. Note that, for unset values, messages and dictionaries may not have consistent behavior. TypeError: If ``msg_or_dict`` is not a Message or Mapping. """

    # We may need to get a nested key. Resolve this.
    key, subkey = _resolve_subkeys(key)

    # Attempt to get the value from the two types of objects we know about.
    # If we get something else, complain.
    if isinstance(msg_or_dict, message.Message):
        answer = getattr(msg_or_dict, key, default)
    elif isinstance(msg_or_dict, collections_abc.Mapping):
        answer = msg_or_dict.get(key, default)
    else:
        raise TypeError(
            "get() expected a dict or protobuf message, got {!r}.".format(
                type(msg_or_dict)
            )
        )

    # If the object we got back is our sentinel, raise KeyError; this is
    # a "not found" case.
    if answer is _SENTINEL:
        raise KeyError(key)

    # If a subkey exists, call this method recursively against the answer.
    if subkey is not None and answer is not default:
        return get(answer, subkey, default=default)

    return answer