question: If there is a reusable water bottle on the left and a disposable bottle on the right.
#1 return water bottle  
#2 return #1 on the  left 
#3 return #1 on the  right 
#4 return if  #2 is reusable 
#5 return if  #3 is disposable 
#6 return if  both  #4 and #5 are true