"one"('one',when python outputs tuple it encloses it in parentheses many programmers emulate this and always enclose the tuple literals they write in parentheses if we have one-item tuple and want to use parentheseswe must still use the comma--for example( ,an empty tuple is created by using empty parentheses(the comma is also used to separate arguments in function callsso if we want to pass tuple literal as an argument we must enclose it in parentheses to avoid confusion tuple here are some example lists type creating and calling functions [ ['alpha''bravo''charlie''delta''echo'['zebra' - 'aardvark' [one way to create list is to use square brackets ([]as we have done herelater on we will see other ways the fourth list shown is an empty list under the hoodlists and tuples don' store data items at allbut rather object references when lists and tuples are created (and when items are inserted in the case of lists)they take copies of the object references they are given in the case of literal items such as integers or stringsan object of the appropriate data type is created in memory and suitably initializedand then an object reference referring to the object is createdand it is this object reference that is put in the list or tuple like everything else in pythoncollection data types are objectsso we can nest collection data types inside other collection data typesfor exampleto create lists of listswithout formality in some situations the fact that liststuplesand most of python' other collection data types hold object references rather than objects makes difference--this is covered in in procedural programming we call functions and often pass in data items as arguments for examplewe have already seen the print(function another frequently used python function is len()which takes single data item as its argument and returns the "lengthof the item as an int here are few calls to len()len(("one",) len([ "pause" ] len("automatically" list type shallow and deep copying