appendix python review as you are probably guessingthere is no need to use the str(constructor explicitly to create string object since we can just specify literal string in our code and have the interpreter automatically create an object for us but the str(constructor can also be used to create string representations of other data typesboth literal values and those referenced by variablesx intstr strx floatstr str boolstr strfalse ' ' 'falsesince python' built-in types are represented as classesthey each have constructor that can be used for creating objects of the given type the following is list of the constructors for the simple typesintx floatx integer floating-point boolx strx boolean string these constructors can also be used to convert between the various types for examplewe can convert the string representation of numeric value to the given numeric type using the appropriate constructori int" float' operations can be performed on objects by invoking method defined for the class of the given type we have already seen the arithmetic operators used with the numeric types but methods can also be defined for use with objects the dot operator is used to apply method to given object for examplewe can create new string that is the lowercase version of an existing string using the lower(method defined by the str classname "jane greennewstr name lower( method is very similar to function with one major difference function is stand-alone subroutine that can be used independent of an objectwhereas method is defined by class and must be applied to an object of that class standard library python is relatively small language but provides the necessary components for creating powerful programs the built-in typeswhich are part of the language itselfhave class definitions defined directly by the language in additionthere are number of built-in functions such as print()input()and abs()that are also provided directly by the language additional functionality is available from various components in the python standard library the standard library contains number of functions and class definitions in which related components are organized into individual files called modules while built-in functions and methods can be used directly within your programthose