Tower of Hanoi python implementation

Schematic diagram:

# 汉诺塔
def hannio(n,a,b,c):
    if n==1:
        print(a ,'-->',c)
        return None
    else:
        hannio(n-1,a,c,b)
        print(a,'-->',c)
        hannio(n-1,b,a,c)

n,a,b,c = 3,'A','B','C'
hannio(n,a,b,c)