(unstack yellow orange robot)
(put-down yellow robot)
(pick-up blue robot)
(stack blue orange robot)
(unstack red green robot)
(stack red blue robot)
(unstack green purple robot)
(stack green yellow robot)
(pick-up purple robot)
(stack purple red robot)
(unstack green yellow robot)
(stack green purple robot)
(pick-up yellow robot)
(stack yellow green robot)