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