```
def mod15(n):
while n >= 15:
n -= 15
return n
# This function should return a value from 0 to 9:
def mod9(n):
# While n is greater or equal to 9, subtract 9 from n:
while n >= 9:
9 -= n
return n
# Don't change the following code:
while True:
time = hero.time
if time < 30:
y = 10 + 3 * mod15(time)
else:
y = 20 + 3 * mod9(time)
x = 10 + time
hero.moveXY(x, y)
```

it says illegal expression for augmented assignment