Write a python function to find the difference between largest and smallest value in a given array.
def big_diff(nums):
     diff= max(nums)-min(nums)
     return diff
<s>[INST]<<SYS>>Given a task and its code, generate test cases for the code.<</SYS>>Write a python function to find the difference between largest and smallest value in a given array.
def big_diff(nums):
     diff= max(nums)-min(nums)
     return diff[/INST]assert big_diff([1,2,3,4]) == 3
assert big_diff([4,5,12]) == 8
assert big_diff([9,2,3]) == 7</s>