def lookup_with_backup(mapping: dict, key: object, backup_key: object) -> object:
    """Return the corresponding value of key in mapping.

    If key is not in mapping, then return the corresponding value of of backup_key
    in mapping instead.

    This assumes that at least one of key and backup_key are a key in map.

    NOTE: the type contract here uses "object" for key, backup_key, and the return type.
    We've included this so that you do *not* need to write any preconditions to check
    for the type of the keys or corresponding values in map.

    Preconditions:
      - key in mapping or backup_key in mapping

    >>> example_dict = {'Burger': 5.0, 'Fries': 3.0}
    >>> lookup_with_backup(example_dict, 'Fries', 'Burger')
    3.0
    >>> lookup_with_backup(example_dict, 'Cheeseburger', 'Burger')
    5.0
    """
    return mapping[key] if key in mapping else mapping[backup_key]