remembermethods need to be called or else they don' do anythingincluding the parentheses to specify the calling argument list tells the interpreter you're calling the method in terms of the "outputof the methodsome methods act like functionreturning their output as return value other methods do their work "in-place,on the object the method is attached tothose methods do not typically have return value the resize method is an example of method that operates on the data in-placewhich is why there is no equal sign (for assignmentassociated with the method call you can also make method operate on an object in-place as well as output return value defining your own class we had said that all objects are instances of classand in the preceding exampleswe looked at what made up string and array instanceswhich tells us something about the class definitions for those two kinds of objects how would we go about creating our own class definitionsclass definitions start with class statement the block following the defining class line is the class definition within the definitionyou refer to the inclass using class stance of the class as self sofor examplethe instance attribute data is called self data in the class definitionand the instance method named calculate is called self calculate in the class definition ( it is called by self calculate()if it does not take any argumentsmethods are defined using the def statement the first argument in any defining methods and method is selfthis syntax is how python tells method "make use of all the self the previously defined attributes and methods in this instance howeverargument you never type self when you call the method usuallythe first method you define will be the init method this the init method method is called whenever you create an instance of the classand so you usually put code that handles the arguments present when you create (or instantiatean instance of class and conducts any kind of initialization for the object instance the arguments list of init is the list of arguments passed in to the constructor of the classwhich is called when you use the class name with calling syntax whewthis is all very abstract we need an examplehere' one this statement is not entirely correct if you do set another variableby assignmentto such method callthat lefthand-side variable will typically be set to none