rapid introduction to procedural programming str( ' the int(conversion is tolerant of leading and trailing whitespaceso int( "would have worked just as well the str(conversion can be applied to almost any data item we can easily make our own custom data types support str(conversionand also int(or other conversions if they make senseas we will see in if conversion failsan exception is raised--we briefly introduce exception-handling in piece # and fully cover exceptions in strings and integers are fully covered in along with other built-in data types and some data types from python' standard library that also covers operations that can be applied to immutable sequencessuch as strings piece # object references |once we have some data typesthe next thing we need are variables in which to store them python doesn' have variables as suchbut instead has object references when it comes to immutable objects like ints and strsthere is no discernable difference between variable and an object reference as for mutable objectsthere is differencebut it rarely matters in practice we will use the terms variable and object reference interchangeably let' look at few tiny examplesand then discuss some of the details "bluey "greenz the syntax is simply objectreference value there is no need for predeclaration and no need to specify the value' type when python executes the first statement it creates str object with the text "blue"and creates an object reference called that refers to the str object for all practical purposes we can say that "variable has been assigned the 'bluestringthe second statement is similar the third statement creates new object reference called and sets it to refer to the same object that the object reference refers to (in this case the str containing the text "blue"the operator is not the same as the variable assignment operator in some other languages the operator binds an object reference to an object in memory if the object reference already existsit is simply re-bound to refer to the object on the right of the operatorif the object reference does not exist it is created by the operator shallow and deep copying