result name is not name result not (name is name we test for null reference with the use of the special value none result name is none result name is not none using functions and methods while python is an object-oriented languageit provides both class structure for object-oriented programming and function structure for procedural programming function is stand-alone group of statementssometimes called subprogramthat performs specific task function is used by invoking it via function call for exampley absx computes the absolute value of variable and stores the result in when function is called during executionthe flow of execution jumps to the functionexecutes its instructionsand then returns to the point where the function was called function call consists of the function name and an argument list enclosed within parenthesesfuncarg arg argn arguments are simply values that are passed to the function for use by that function the number of arguments passed to function depends on the specific function when multiple arguments are passed to functionthey are separated with commas and passed in the order specified by the function header if function requires no argumentsthe parentheses are still required some functions may return value this value can be used or ignored depending on the purpose of the function if function returns valuethe function call can be used anywhere value of the given type can be used for examplesince the abs(function returns numeric valueit can be used as part of an arithmetic expressiony absx as indicated earlierall values in python are stored in objects that are created or instantiated from classes once an object has been createdit can then be used objects are automatically instantiated or created for all literal values within program but we can also explicitly create objects by calling the constructor of the corresponding class for the given type of object for examplewe can create string object by calling the constructor of the str classname str"jane green