def dict_zero(first_level_keys):
    """Initialise a dictionary with one level

    Parameters
    ----------
    first_level_keys : list
        First level data

    Returns
    -------
    one_level_dict : dict
         dictionary
    """
    one_level_dict = dict.fromkeys(first_level_keys, 0) # set zero as argument

    return one_level_dict