anchor.diff:  	m.erase(it);
   	it.destroy();
   
  -	if check(m, '1 -2 -1 3 4 5') then
  -		writeln('Ok')
  -	else
  -		writeln('Foo');
  +	check(m, '1 -2 -1 3 4 5');
   	
   	m2 := container.create();
   	while not m.empty() do
  
positive.code: 	m.insert(it, -3);
  	it.destroy();
  
  	if check(m, '1 2 -3 -2 -1 3 4 5') then
  		writeln('Ok')
  	else
  		writeln('Foo');
  
  	it := m.get_begin();
  	it.next();
  
negative.code: 	writeln(to_str(c));
  end;
  
  function equal(c: container; pattern: string): boolean;
  begin
  	check := to_str(c) = pattern;
  end;
  
  procedure check(c: container; pattern: string);
  begin
  	if equal(c, pattern) then
  		writeln('Ok')
  	else
  		writeln('Foo');
  end;
  
  procedure test();
  