anchor.diff:  		m_prev := nil;
   	end;
   
  +	destructor link.destroy();
  +	begin
  +		m_next := nil;
  +		m_prev := nil;
  +	end;
  +	
   	procedure link.set_next(pLink: link);
   	begin
  -		m_next := link;
  +		m_next := pLink;
   	end;
   
   	procedure link.set_prev(pLink: link);
   	begin
  -		m_prev := link;
  +		m_prev := pLink;
   	end;
   
   	constructor iterator.create(l: link);
  
positive.code: 		iterator = class
  		public
  			constructor create(l: link);
  			
  			procedure next();
  			procedure prev();
  			
  
negative.code: 		container = class
  		public
  			constructor create();
  			destructor destroy();
  			
  			function get_begin(): iterator;
  			function get_end(): iterator;
  