Calculate T(n), making sure not to discard constants or low-order terms yet (you may or may not count the counting variable in a for loop)

Give what you think is the Big-O performance for the function

Prove that your proposed Big-O for the function is correct (make sure to show your work; do not just provide values for c and n0)

def fun2(n): x = 0 for i in range(n): for j in range(n): for k in range (1, n): x = x + 1 return x def fun3 (n): x = 0 i = 2 * n while i >= 1: x = x - i i = i - 1 return X