Current State ID: 16
Current State Description: Block `a` is on the table and clear. Block `b` is on the table and not clear, holding block `c`. Block `c` is on block `b` and clear. Block `d` is on the table and clear. The hand is empty.

Child State ID: 28
Action Taken: unstack(c, b)
State Description: Block `a` is on the table and clear. Block `b` is on the table and clear. Block `c` is in the hand and not clear. Block `d` is on the table and clear. The hand is holding block `c`.

