Current State ID: 3
Current State Description: There are four blocks: a, b, c, and d. The hand is empty. Block a is on the table. Block d is on top of block a and is clear. Block b is on the table and is clear. Block c is now on the table and clear.

Child State ID: 6
Action Taken: unstack(d, a)
State Description: There are four blocks: a, b, c, and d. The hand is holding block d. Block a is on the table and clear. Block b is on the table and clear. Block c is on the table and clear. Block d is no longer on block a.

