import contextlib


@contextlib.contextmanager
def make_context():
    print('  entering')
    try:
        # Yield control, but not a value, because any value
        # yielded is not available when the context manager
        # is used as a decorator.
        yield
    except RuntimeError as err:
        print('  ERROR:', err)
    finally:
        print('  exiting')


@make_context()
def normal():
    print('  inside with statement')


@make_context()
def throw_error(err):
    raise err


print('Normal:')
normal()

print('\nHandled error:')
throw_error(RuntimeError('showing example of handling an error'))

print('\nUnhandled error:')
throw_error(ValueError('this exception is not handled'))
