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The code in this statement’s main-action block is executed first, as usual. If that coderaises an exception, all the except blocks are tested, one after another, looking for amatch to the exception raised. If the exception raised is Exception1, the handler1block is executed; if it’s Exception2, handler2 is run, and so on. If no exception israised, the else-block is executed.No matter what’s happened previously, the finally-block is executed once the mainaction block is complete, and any raised exceptions have been handled. In fact, thecode in the finally-block will be run even if there is an error in an exception handler,or the else-block and a new exception is raised.As always, the finally clause does not end the exception—if an exception is activewhen the finally-block is executed, it continues to be propagated after the finallyblockruns, and control jumps somewhere else in the program (to another try, ortothe default top-level handler). If no exception is active when the finally is run, controlresumes after the entire try statement.The net effect is that the finally is always run, regardless of whether:• An exception occurred in the main action and was handled.• An exception occurred in main action and was not handled.• No exceptions occurred in the main action.• A new exception was triggered in one of the handlers.Again, the finally serves to specify cleanup actions that must always occur on theway out of the try, regardless of what exceptions have been raised or handled.Combining finally and except by NestingPrior to Python 2.5, it is actually possible to combine finally and except clauses in atry by syntactically nesting a try/except in the try block of a try/finally statement(we’ll explore this technique more fully in Chapter 29). In fact, the following has thesame effect as the new merged form shown in the previous section:try:try:main-actionexcept Exception1:handler1except Exception2:handler2...else:no-errorfinally:clean-up590 | Chapter 27: Exception Basics