''' Modules ------- In python each python file is considered as a module. In java, we need not specify import of the package if the class we use is within same package. But in python whether if the file we refer is in same directory/package then also we need to specify 'import' of that. NOTE : We should not use '_' in file names because when we import that module. if name contains '_', it will not find that file. ''' # When we import any module. python will literally execute that file/module. In this case, 'Addition.py' have # print statement "Start of Addition Module" and then definition of function 'addition()'. # So in below statement, we import 'Addition.py' so it is executed and prints "Start of Addition Module" import Addition as add # Output --> "Start of Addition Module" # NOTE : due to this we should always put whatever we want to do within function definitions instead of putting it # outside. because when we import a module, we don't want something to be executed in that file, we just # import that module in our file. print(add.addition(5, 3)) # Output --> 8 import packageY.Substraction as sub # Importing a module within different package. Syntax --> 'Package.module' print(sub.substraction(5, 3)) # Output --> 2