Current State ID: 35
Current State Description: Block 'a' is held in the hand. Block 'b' is on the table and clear. Blocks 'c' and 'd' are on the table and clear. The hand is holding block 'a'. The diagram would show block 'a' marked as held, with the hand no longer empty.

Child State ID: 43
Action Taken: stack(a, b)
State Description: Block 'a' is on top of block 'b'. Block 'b' is on the table and supporting block 'a'. Blocks 'c' and 'd' are on the table and clear. The hand is empty. The diagram would show block 'a' on block 'b', with block 'b' marked as supporting and the hand empty.

