Maybe construct this like we do in other examples, and make it have at least 2 nodes?
```python
>>> G = nx.Graph()
>>> G.add_edge(0,1)
>>> G.add_edge(1,1)
>>> A = nx.to_numpy_matrix(G)
>>> A
matrix([[ 0.,  1.],
        [ 1.,  1.]])
>>> A.A[np.diag_indices_from(A)] *= 2
>>> A
matrix([[ 0.,  1.],
        [ 1.,  2.]])
```