[ the del statement is statementnot function or an operator it doesn' have parentheses or evaluate to return value lists of lists lists can contain other valuesincluding other lists let' say you have list of groceriesa list of choresand list of your favorite pies you can put all three lists into another list try entering the following into the interactive shellgroceries ['eggs''milk''soup''apples''bread'chores ['clean''mow the lawn''go grocery shopping'favoritepies ['apple''frumbleberry'listoflists [grocerieschoresfavoritepieslistoflists [['eggs''milk''soup''apples''bread']['clean''mow the lawn''go grocery shopping']['apple''frumbleberry']to get an item inside the list of listsyou would use two sets of square brackets like thislistoflists[ ][ which would evaluate to the string 'go grocery shoppingthis is because listoflists[ ][ evaluates to ['clean''mow the lawn''go grocery shopping'][ that finally evaluates to 'go grocery shopping'listoflists[ ][ [['eggs''milk''soup''apples''bread']['clean''mow the lawn''go grocery shopping']['apple''frumbleberry']][ ][ ['clean''mow the lawn''go grocery shopping'][ 'go grocery shoppingfigure - is another example of list of listsalong with some of the indexes that point to the items the arrows point to indexes of the inner lists themselves the image is also flipped on its side to make it easier to read methods methods are functions attached to value for exampleall string values have lower(methodwhich returns copy of the string value in lowercase you can call it like 'hellolower()which returns 'helloyou cannot call lower(by itself and you do not