I honestly have no idea what to put on line 15 please explain.

```
# Walk through the minefield
# This function returns the number multiplied by the times
def mult(number, times):
total = 0
while times > 0:
total += number
times -= 1
return total
# This function returns the number to the exponent power.
def power(number, exponent):
total = 1
# Complete the function.
return total
# Don't change the following code
# You can find coefficients for the equation on the tower
tower = hero.findFriends()[0]
a = tower.a
b = tower.b
c = tower.c
d = tower.d
x = hero.pos.x
while True:
# To find the path use a cubic equation
y = a * power(x, 3) + b * power(x, 2) + c * power(x, 1) + d * power(x, 0)
hero.moveXY(x, y)
x = x + 5
```