The Grocery Algorithm
to the tune of... <pick your own tune>
drive to grocery store
get trolley
enter store

for each item on the list:
  find it
    pick it up 
    put it in the trolly.
find the checkout line that looks shortest
(note: it's not the quickest)
while people are in front of you: do nothing.
  for each item in the trolley:
    pick it up 
    put it on the conveyor belt.

[Now we'll switch over to look at the cashier program]
  
greet customer.  
for each item on the conveyor belt
  pick it up 
  scan it
  no bag on bag holder?
    pick up an empty bag
    put it on the bag holder
  put the item in a bag.
  bag full?
    pick up the bag
    put it down the end of the counter.
tell customer the price
take money
put it in the till
give change.
  
[switch over to look at the customer  program again]
  
for each bag on the counter:
  pick it up
  put it in the trolley
    
push trolley to car.
open boot. (i.e. 'trunk')
  
for each bag in the trolley:
  pick it up
  put it in boot (i.e. 'trunk')

push trolley out of the way.    
drive home
  
open boot.
  
do while bags left in boot:
  while i have the strength to carry one more bag:
    pick up a bag.
  no bags left in car?
    close boot (i.e. 'trunk')   
  walk up stairs
  walk to kitchen counter
  while bag/bags in my hands:
    put it on kitchen counter
  bags left in car? so walk downstairs

  
for each bag on the kitchen counter
  while items remain in bag
    pick up item
    put item away