python
F=GF(2^8,'a')
R=PolynomialRing(F,"x,y")
R.inject_variables()
f=x*y-1
How can we transform f
into a multivariable Boolean polynomial over $\mathbb{F}_{2^8}$, which includes variables $x_0, \ldots, x_7$ and $y_0, \ldots, y_7$ (16 variables in total), and has an algebraic degree of 2?