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