Trying to complete the number guess portion of learn Python and repeatedly getting an error on step 17. The error is “max_val” is not defined when I try to guess a number higher than the limitations I have programmed. Copied the code below. Any help is greatly appreciated.

```
"This program rolls a pair of dice and compares the outcome to your guess."
from random import randint
from time import sleep
def get_user_guess():
guess=int(raw_input("Guess a number"))
return guess
def roll_dice(number_of_sides):
first_roll=randint(1, number_of_sides)
second_roll=randint(1, number_of_sides)
max_val = number_of_sides * 2
print "The maximum number of sides is %d" % max_val
guess=get_user_guess()
if guess > max_val:
print "Guess is invalid"
roll_dice(6)
```