Some number of white lego bricks and red lego bricks are put into a bag. A transition and an observation happens every round.
1. A random brick is removed from the bag, and a replacement brick that is equally likely to be red or white is added to the bag.
2. Then you pull another random brick from the bag, observe color, and replace.

Fill in the blank with appropriate probabilities. The default setting starts with two white lego bricks in the bag. You may change the number of blocks on the right column and start over.