nump array code example
Example: numpy array [-1]
print(b)
>>array([[ 0, 1, 2, 3],
[10, 11, 12, 13],
[20, 21, 22, 23],
[30, 31, 32, 33],
[40, 41, 42, 43]])
print(b[-1]) # the last row. Equivalent to b[-1,:]
>>array([40, 41, 42, 43])