anchor.diff:  
   	procedure list.insert(p: list_iterator; data: longInt);
   	var
  -		link, nextLink, prevLink: pLink;
  +		link, nextLink, prevLink: list_link_pointer;
   	begin
   		new(link, create(data));
   		if empty() then
  
positive.code: 	destructor list.destroy();
  	begin
  		while not empty() do
  			erase(m_begin);
  		dispose(m_end.getLink());
  	end;
  
  
negative.code: 
  	procedure list.erase(p: list_iterator);
  	var
  		nextLink, prevLink, curLink: list_link_pointer;
  	begin
  		if p.equal(m_end) then
  			exit();
  