def fib_r(n: int) -> int:
    """Recursively the nth fibonacci number

    :param n: nth fibonacci sequence number
    :type n: int
    :returns: the nth fibonacci number
    :rtype: int

    .. doctest:: python

        >>> fib_r(1)
        1
        >>> fib_r(2)
        2
        >>> fib_r(6)
        13

    """
    return n if n < 3 else fib_r(n - 1) + fib_r(n - 2)