ValueError: Currently, only builders without or 
with a 1D translational
 symmetry can be finalized.

Is there any solution to this?

I also happen to get one code from notes on internet by 
edx course where thwe following code has been used using wraparound function.

I did not get much out of it. Also, I checked I don't have this function in my kwant module. how can I get this functions module?
Please anyone can explian what this function is doing in the code:

def make_scatter_sys():
    from functions import wraparound
    syst = wraparound(bhz(Z=1, system_type='slab'))
    syst.attach_lead(make_lead())
    syst.attach_lead(wraparound(bhz(), keep=0))
    syst = syst.finalized()
    syst.leads[0] = TRIInfiniteSystem(syst.leads[0], trs)
    return syst