GSPLIT _ _ _ _ _ _ _ _ _ _ _ _ operator
where <p> is a polynomial or a list of polynomials.
The polynomial is reordered corresponding to the the current term order and then separated into leading term and reductum. Result is a list with the leading term as first and the reductum as second element.
torder lex; gsplit(x**2+2x*y+y**2,{y,x}); {y**2,2y*x+x**2}