Simplest snippet that investigates how "with" works in Python.

how_with_works_in_python.py

class Klass:
    def __init__(self):
        print("instanciated")

    def __del__(self):
        print("gabage collected")

    def __enter__(self):
        print("__enter__")
        return self

    def __exit__(self, execution_type, execution_value, traceback):
        print("__exit__")
        self.close()

        print("execution type: ", execution_type)
        print("execution value: ", execution_value)
        print("traceback: ", traceback)

    def do_something(self):
        print("do something")

    def close(self):
        print("close!!1!!")

def main():
    with Klass() as instance:
        instance.do_something()

if __name__ == "__main__":
    main()