The miracle of python is that it has standard syntax for vectorized code across many packages.

    For i in range(100):
    mask = lib.abs2(z) < 4
    subset = z[mask]
    subc = c[mask]
    subcounts = 0
    for j in range(100):
        subcounts = subcounts + lib.abs2 (subset )< 4
        subz = subz**2 + subc
    Z[mask] = subset
    Counts[mask]  += subcounts

Was that code using numpy, tensorflow, torch, arrayfire, or some proprietary amd gpu lib? It’s hard to say!

Try the same with eigen vs arrayfire in C++ or math.js vs tensorflow.js and you will have to do a hell of a lot more than change the value of lib