Mod(0,2)*x*1.
Pol(Mod(0,2)) + 2
Mod(1,2)+Pol(Mod(1,2))
Ser(Mod(1,2)) + 1
(2+0*I)+I*Mod(0,4)
a=b=Mod(2, 4) + Mod(2, 4)*I; a*b
(Mod(0,2)+I)^2
Mod(0,2)/x
a=Mod(1, 2)*x^10 + Mod(1, 2); 2*a
a+a
valuation(Mod(0,101),101)
gcd(Mod(0,5),10)
gcd(Mod(0,5),Mod(0,10))
{
v = [[0,0,0,0], [0,0,0,Mod(0,2)], [1,0,0,Mod(0,2)],
     [1,0,0.,Mod(0,2)], [1,0,Mod(0,2),0.]];
for (i = 1, #v,
  w = v[i];
  print1(Pol(w), " ");
  print1(Polrev(w), " ");
  print1(Ser(w), " ");
  w = vecextract(w, "-1..1");
  print1(Pol(w), " ");
  print1(Polrev(w), " ");
  print1(Ser(w), " "); print();
)
}
