exit a program gracefully

[Lawrence D'Oliveiro]

In message <mailman.5079.1241476454.11746.python-list at python.org>, Gabriel 
Genellina wrote:

> I prefer to put the code inside a function, and just `return` earlier.

It would be nice if Python offered a straightforward equivalent to

    ... initialization goes here ...
    do /*once*/
      {
        ... do stuff ...
        if (check1_failed)
            break;
        ... do more stuff ...
        if (check2_failed)
            break;
        ... do even more stuff ...
      }
    while (false);
    ... cleanup goes here ...