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In the third book, near Figure 10, you mention plotting using plot.ly as a free online plotting tool. Unfortunatly I think they shifted to a paid subscription or an account system. As an alternative, I would suggest Desmos 3D. In this 3d math plotter you can enter points by entering (x_val, y_val, z_val) on a line to plot said point. The code in Listing 23 should then change to printing "(x,y,z)\n" instead. Because this is a math plotter, you can also enter the formula of a unit sphere, x^2 + y^2 + z^2 = 1.
It is a small change, but I think it could save others a bit of time Googling if you add this. Alternatives can never hurt ;)