def aq(string):
    """
    Add the quotes " characters around a string if they are not already there.
    Parameters
    ----------
    string : str
        just a string to be formatted
    Returns
    -------
        str
        a string with " character at the beginning and the end
    """
    tmp = string
    if not string.startswith('"'):
        tmp = '"' + tmp
    if not string.endswith('"'):
        tmp = tmp + '"'
    return tmp