>>> x = np.array(range(10))
>>> y = x
>>> z = x.copy()
>>> y
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> y[1] = 11
>>> x
array([ 0, 11, 2, 3, 4, 5, 6, 7, 8, 9])
>>> z
>>>