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