"""The Code, that follows Inversion of Control principle.""" class Service(object): """Some "Service".""" class Client(object): """Some "Client" that uses "Service".""" def __init__(self, service): # Service instance is injected in Client """Initializer.""" self.service = service if __name__ == '__main__': # Application creates Service instance service = Service() # and inject Service instance into the Client client = Client(service)