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