if you are curiousthe source code for complete tic-tac-toe program is described in the resources available from nested dictionaries and lists modeling tic-tac-toe board was fairly simplethe board needed only single dictionary value with nine key-value pairs as you model more complicated thingsyou may find you need dictionaries and lists that contain other dictionaries and lists lists are useful to contain an ordered series of valuesand dictionaries are useful for associating keys with values for examplehere' program that uses dictionary that contains other dictionaries of what items guests are bringing to picnic the totalbrought(function can read this data structure and calculate the total number of an item being brought by all the guests allguests {'alice'{'apples' 'pretzels' }'bob'{'ham sandwiches' 'apples' }'carol'{'cups' 'apple pies' }def totalbrought(guestsitem)numbrought for kv in guests items()numbrought numbrought get(item return numbrought print('number of things being brought:'print(apples str(totalbrought(allguests'apples'))print(cups str(totalbrought(allguests'cups'))print(cakes str(totalbrought(allguests'cakes'))print(ham sandwiches str(totalbrought(allguests'ham sandwiches'))print(apple pies str(totalbrought(allguests'apple pies'))you can view the execution of this program at /guestpicnicinside the totalbrought(functionthe for loop iterates over the key-value pairs in guests inside the loopthe string of the guest' name is assigned to kand the dictionary of picnic items they're bringing is assigned to if the item parameter exists as key in this dictionaryits value (the quantityis added to numbrought if it does not exist as keythe get(method returns to be added to numbrought the output of this program looks like thisnumber of things being broughtapples cups cakes ham sandwiches apple pies this may seem like such simple thing to model that you wouldn' need to bother with writing program to do it but realize that this same totalbrought(function could easily handle dictionary that contains dictionaries and structuring data