Current State ID: 21
Current State Description: Block A is now on block B and is clear. Block B is on block D and is not clear. Block C is on the table and is clear. Block D is on the table and is not clear. The hand is empty.

Child State ID: 28
Action Taken: unstack(block_a, block_b)
State Description: Block A is in the hand and is not clear. Block B is clear and on block D, which is not clear. Block C is still on the table and clear. Block D remains on the table and is clear. The hand is holding block A.

