REMOVES DUPLICATES from a list. 
		
		   ?- remove_duplicates([a,b,a,b,b,c],I).
		   I = [a,b,c].
		   ?- remove_duplicates([a,b],I).
		   I = [a,b].
		   	
		remove_duplicates([],[]):- !.
		remove_duplicates([H|T],R):- member(H,T),remove_duplicates(T,R),!.
		remove_duplicates([H|T],[R|Rest]):- remove_duplicates(T,Rest).