Current State ID: 11
Current State Description: Block 'a' is held by the hand and not clear. Block 'b' is on the table and clear. Block 'c' is on the table and clear. Block 'd' is on the table and clear. The hand is holding block 'a'.

Child State ID: 12
Action Taken: stack(block_a, block_c)
State Description: Block 'a' is on block 'c' and clear. Block 'b' is on the table and clear. Block 'c' is on the table and supporting block 'a'. Block 'd' is on the table and clear. The hand is empty.

