3 3 x *y + x*y
x^3*y + x*y^3
/ 2 2\ x*y*\x + y /
x*y*(x^2 + y^2)
1*(x + 0)*(x + I*y)*(x - I*y)*(y + 0)
(((1*(x + 0))*(x + i*y))*(x - i*y))*(y + 0)
x*y^3 + y*x^3