Interestingly, Python has the "with" statement for this basic genre of operation (executing a block of code while some particular resource is held), although it

Interestingly, Python has the "with" statement for this basic genre of operation (executing a block of code while some particular resource is held), although it doesn't require that the third, "undo" step be automatically derived from the first step - it's just a protocol where a 'start' and 'end' method are called on the object representing the resource. It sure makes it easy to be sure you're closing your file handles/database connections/mutexes, though.