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: 		equal := m_link = other.m_link;
  	end;
  
  	function list_iterator.getLink(): pLink;
  	begin
  		getLink := m_link;
  	end;
  
  	constructor list.create();
  	var
  		link: pLink;
  	begin
  		new(link, create(0));
  		m_begin := list_iterator.create(link);
  
negative.code: 		m_prev := nil;
  	end;
  
  	procedure list_link.setNext(link: list_link_pointer);
  	begin
  		m_next := link;
  	end;
  
  	procedure list_link.setPrev(link: list_link_pointer);
  	begin
  		m_prev := link;
  	end;
  
  	constructor list_iterator.create(l: list_link_pointer);
  	begin
  		m_link := l
  	end;
  