Thank you @TMosh.
Yes, I tried using np.float(b) after I’d found your response here.
But no luck.
I tried two routes. The first one being Z = np.float(Z + np.float(b)), which makes most sense to me because it yields a scalar. So it does. And the scalar is correct. But I get the error. Then I tried Z = Z + np.float(b). That doesn’t make sense to me because it results in a numpy array (with one value). The value itself is correct. But again, I get the same error. Adding 64 or 32 doesn’t make any difference.
Ivan
P.S. After playing with np.float() - literally by adding it and removing it and by adding 64 and removing it - I’ve got the test passed. May be the notebook got out of stuck finally … But thank you very much TMosh!