Examples:
		?- last([a],R)
		R=a
	  	?-last([a,b,1,c],X).
	 	X=c
	  	?-last([a,b,[c,[d]]],X).
	  	X=[c,[d]]
	  	Solution 1.	

		last([X],X).
		last([H|T],R):- last(T,R).
		Solution 2.	

		last(L,R):- append(_,[R],L).
		
		append/2 is a Prolog predicate:
		
		append([],Y,Y).
		append([H|T],Y,[H|R]):- append (T,Y,R).