Trailing coefficient degree of a polynomial : tcoeff

tcoeff takes as argument a polynomial given by a symbolic expression or by the list of its coefficients.
tcoeff returns the coefficient of the monomial of lowest degree of this polynomial (tcoeff=trailing coefficient).
Input :

tcoeff([2,1,-1,0])

Output :

-1

Input :

tcoeff(3*x^2+5*x,x)

Output :

5

Input :

tcoeff(3*x^2+5*x*y^2,y)

Output :

3*x^2