python. Convert dict keys to uppercase. If you want to use it - don't. This mean that you should change your code.

upper.py

def _uppercase_for_dict_keys(lower_dict):
    upper_dict = {}
    for k, v in lower_dict.items():
        if isinstance(v, dict):
            v = _uppercase_for_dict_keys(v)
        upper_dict[k.upper()] = v
    return upper_dict


def test():
    examined = {
        'a': 1,
        'b': {
            'c': 3,
        }
    }
    expected = {
        'A': 1,
        'B': {
            'C': 3,
        }
    }
    assert _uppercase_for_dict_keys(examined) == expected


if __name__ == '__main__':
    test()