# cannot use .str() on kernel of Matrix ?

(with sagemath 10.1 - not checked with previous revision)

A is a matrix defined by:

```
A=Matrix(GF(2),4,3,[0,1,1,1,0,1,1,1,0,1,1,1])
```

k is the kernel of A :

```
k=kernel(A)
```

Sagemath displays :

```
Vector space of degree 4 and dimension 1 over Finite Field of size 2
Basis matrix:
[1 1 1 0]
```

But then, k.str() fails with error message **"AttributeError: 'FreeModule_submodule_field_with_category' object has no attribute 'str'".**