Why is this not working? Can you help please? :     import turtle as t
    t.setup(500,500)
    t.setworldcoordinates(0,0,500,500)
    t.pu()
    t.goto(0,0)
    t.pd()
    t.seth(0)
    def N():
        t.pu()
        t.pd()
    def B(c,d):
        t.right(90)
        c
        t.forward(5)
        t.left(90)
        d
        t.forward(5)
        d
        t.left(90)
        t.forward(5)
        c
        t.right(90)
    def A(a,b):
        t.left(90)
        b
        t.forward(5)
        t.right(90)
        a
        t.forward(5)
        a
        t.right(90)
        t.forward(5)
        b
        t.left(90)      
    t.seth(0)
    A(A(None,None),B(None,None))

> I'm Trying to make the Hilbert curve
> But it is not working
> I am using the l system
> rsrgwerbwv
> viewbviqe
> nvenlvnqebfv
> ndjvnlenbnwr
> dnvonwvqe
> ijdbvqepv p;e
> nnweone[qro[nv
> jdbdijvqejv
> jsvjn[afb
> njnvonadzb
> ksnjvnasv