def init_nested_dict_brackets(first_level_keys, second_level_keys):
    """Initialise a nested dictionary with two levels

    Arguments
    ----------
    first_level_keys : list
        First level data
    second_level_keys : list
        Data to add in nested dict

    Returns
    -------
    nested_dict : dict
        Nested 2 level dictionary
    """
    nested_dict = {}

    for first_level_key in first_level_keys:
        nested_dict[first_level_key] = {}
        for second_level_key in second_level_keys:
            nested_dict[first_level_key][second_level_key] = {}

    return nested_dict