How to fix this code. I keep getting assertion error.

$1\mathrm{.}2[2$ pt$]$ Write a function called det$\_$and$\_$inv that takes as an input a square matrix $($a numpy array$)$ and returns a tuple with two elements $($a$)$ the determinant, and $($b$)$ the inverse if it mathematically exists and the string "does not exist" otherwise.

In $[12]$: import numpy as np

def det$\_$and$\_$inv$($matrix$)$:

det$=$np$.$linalg.det$($matrix$)$

if det $!=0$:

Inv$=$np$.$linalg.inv$($matrix$)$

return det,inv

Else:

return det, "does not exist"