def possessive(string):
    """
    Determines whether to place an 's or just an ' at the end of a string, to represent possession.

    Arguments:
        string (string): The string to evaluate.
    
    Returns:
        string (string): The final result with the attached possession.
    """
    if string[-1] == 's':
        string = f"{string}\'"
    else:
        string = f"{string}'s"
    return string