def f4(a1,a2):
print(a1,a2)
if a1>1000:
return
#a1=0;a2=1;a3=1
#a1=1;a2=1;a3=2
a3 = a1 + a2
f4(a2,a3)
f4(0,1)
斐波那契数列第十个数
def f5(depth,a1,a2):
print(depth)
if depth == 10:
return a1
a3=a1+a2
r = f5(depth+1,a2,a3)
return r
ret =f5(1,0,1)