sbool <A> eqMatrices(Matrix<A> a, Matrix<A> b) {
  if (a == null || b == null) ret a == b;
  int w = a.getWidth(), h = a.getHeight();
  if (b.getWidth() != w || b.getHeight() != h) false;
  for y to h:
    for x to w:
      if (!eq(a.get(x, y), b.get(x, y))) false;
  true;
}