def fib_rec(n):
    """
    A recursive function calcuating Fibonnaci sequence

    Parameters
    ----------
    n : integer
        the nth Fibonnaci number in the sequence

    Returns
    -------
    recursively calling fib_rec to calculte Fibonnaci number.
    Will return the nth Fibonnaci number

    """
    if n == 0:
        return 0
    if n == 1:
        return 1
    return(fib_rec(n-2) + fib_rec(n-1))