$$ Whats wrong with the code? I keep getting assertion error

$4\mathrm{.}3[2pt$ What $22$ matrix, with integer entries, has $10$ and $25$ as eigenvalues with eigenvectors $1,4$ and $1,-1,$ respectively? Store it in the variable matrix$\_$answer.

Hint: Put variables for entries in a $22$ array $([a_{11},a_{12}],[a_{21},a_{22}]),$ write out the equations that must be satisfied, and solve for the entires.

In $[31]$: import numpy as np

$A=np.$array$(\left[\begin{array}{cc}1& 4\\ 1& -1\end{array}\right])$

vals, vecs$=np.$linalg$*eig(A)$

if np$.$iscomplex$($vals$).$ any$()$:

vals $=$vals.real

if np$.$iscomplex$($vecs$),$ any$()$:

vecs $=$ vecs $.$ real

$a11=$vals$[]$

$a12=$vecs$[][1]$

a$21=$vecs$[1][]$

$a22=$vals$[1]$

matrix$\_$answer$=$ np$.$array $(\left[\begin{array}{cc}a11& a12\\ a21& a22\end{array}\right])$

print $($matrix$\_$answer$)$