Write numeric_grad(f, x, eps=1e-6) — the central-difference slope (f(x+eps) - f(x-eps)) / (2eps) — and use it to referee the autograd on y = ww + w at w=3. Print the autograd gradient, the numeric one (rounded to 5), and whether they match within 1e-4. Note what the autograd got right without being told: w appears twice, and accumulation sums both paths' contributions.