# Usually pretty much any code is error-prone, and not because you're bad # programmer (be sure - you are, I am as well bad programmer), but because # environment is wild and dangerous. Lets calculate sum of all numbers from # `integers.txt` file, single integer per line. # Too much constrints to let this code be alive so easily... try: with open('integers.txt') as f: numbers = map(int, f.readlines()) total = sum(numbers) if total > 10: raise OverflowError("More than I can handle") print total # What if there's no such file? Stop code? except IOError as e: print "IOError: {0}".format(e) # What if there's wrong value to be an integer? Or you forget to split lines? except ValueError as e: print "ValueError: {0}".format(e) # Ok, now it's your own fault... except OverflowError as e: print "OverflowError: {0}".format(e) # But if nothing happens, then you can surely execute `esle` statement else: print "Whoooo! That was close..."