After a suit is led

The lead is a heart, and a heart is still in your hand.

The next card is a heart. A diamond, a club, or a spade stays down.

Hearts were led, and your hand has no heart.

The follow rule lifts. Any suit you hold can come down.

You took the stop.

The next stop starts with one punch. Spending it shows one card that is still face down in the conductor's hand.

The stop was lost, or none has been taken yet.

There is no punch. The conductor's other cards stay face down for that stop.