def one_or_more(amount, single_str, multiple_str):
    """
    Return a string which uses either the single or the multiple form.

    @param amount the amount to be displayed
    @param single_str the string for a single element
    @param multiple_str the string for multiple elements

    @return the string representation

    """
    if amount == 1:
        ret_str = single_str
    else:
        ret_str = multiple_str
    return ret_str.format(amount)