Current State ID: 0
Current State Description: The hand is empty. Block 'a' is on the table. Block 'd' is on top of block 'a'. Block 'c' is on top of block 'd'. Block 'b' is on top of block 'c'. Block 'b' is clear, meaning there is no block on top of it.

Child State ID: 1
Action Taken: unstack(b, c)
State Description: The hand is holding block 'b'. Block 'a' is on the table. Block 'd' is on top of block 'a'. Block 'c' is on top of block 'd' and is now clear. Block 'b' is no longer on block 'c'. The hand is not empty, and block 'c' is clear.

