def join(first_value, second_value, join_value='/'):
    """
    Joins two string making sure that the join value is
    not repeated in the "join point" (no double join).
    The "join point" is guaranteed to be unique.

    :type first_value: String
    :param first_value: The first string to be joined.
    :type second_value: String
    :param second_value: The second string to be joined.
    :type join_value: String
    :param join_value: The join value to be verifies and
    used in the "join point".
    :rtype: String
    :return: The joined string ensured to be with a single
    join point (not repeated).
    """
    first_value = not first_value.endswith(join_value
        ) and first_value or first_value[:-1]
    second_value = not second_value.startswith(join_value
        ) and second_value or second_value[1:]
    string_value = join_value.join((first_value, second_value))
    return string_value
