def standardize_bool_hors_nk(hors_nk_str):
    """This column contains string while it could be a boolean. To ease future data manipulation,
    let's convert it to a boolean, with a value of 1 if the data is not in Nouakchott, and 0 is the
    data is from Nouakchott. It returns None if we can't recognize the string in argument.

    Args:
        hors_nk_str (str): string in the column

    Returns:
        boolean (int): 0 or 1.
    """
    if hors_nk_str == "Hors Nouakchott":
        return 1
    if hors_nk_str == "Nouakchott":
        return 0
    else:
        return None