Current State ID: 17
Current State Description: Block 'a' is on the table and clear. Block 'c' is on top of block 'b' and is now supporting block 'd'. Block 'b' is on the table. Block 'd' is on top of block 'c' and is clear. The hand is empty.

Child State ID: 19
Action Taken: unstack(d, c)
State Description: Block 'a' is on the table and clear. Block 'c' is on top of block 'b' and clear. Block 'b' is on the table. Block 'd' is held in the hand and no longer on block 'c'. The hand is not empty.

Child State ID: 20
Action Taken: pick-up(a)
State Description: Block 'a' is held in the hand. Block 'c' is on top of block 'b' and is supporting block 'd'. Block 'b' is on the table. Block 'd' is on top of block 'c' and is clear. The hand is holding block 'a'.

