Empty triangle against first line hane

Mistake  

If White mindlessly plays the hane connect of against , Black can surprise her by cutting at . When captures, is atari. Next, ...

Mistake  

if connects, will capture the stones by driving them to the right, usually, because that's where Black's territory lies, since this was an endgame problem to start with.

Correct  

This empty triangle of may look like bad shape but this is correct endgame play under normal conditions.

Mistake  

Incidentally, higher level players who recognize the danger, may be tempted to play "good shape" with . As can be easily compared, White is two points worse off here.

Danger?  

This is the kind of danger, White is fearing in the previous diagram. Under endgame conditions White should be able to determine whether such a sequence would achieve something or not.