anchor.diff:  
   	procedure Vector.push_back(element: integer);
   	begin
  -		if length = capacity then
  -		begin
  -			capacity := 3 * capacity div 2 + 1;
  -			setLength(data, capacity);
  -		end;
  -		data[length] := element;
  -		length := length + 1;
  +		insert(finish(), element);
   	end;
   
   	procedure Vector.insert(p: Iterator; element: integer);
   	var
   		tail: Iterator;
  +		index, i: integer;
   	begin
  +		index := p.raw() - start().raw();
  +		
   		if length = capacity then
   		begin
   			capacity := 3 * capacity div 2 + 1;
  
positive.code: 	begin
  		at := data[num];
  	end;
  end.
  
negative.code: 		end;
  		length := length + 1;
  
  		for i := length downto index + 1 do
  			data[i] := data[i-1];
  
  		data[index] := element;
  	end;
  
  	function Vector.start(): Iterator;
  