finallynote that the runtime execution model sketched here is really an artifact of the current implementation of pythonnot of the language itself for instanceit' not impossible that fulltraditional compiler for translating python source code to machine code may appear during the shelf life of this book (although the fact that one has not in over two decades makes this seem unlikely!new byte code formats and implementation variants may also be adopted in the future for instancethe ongoing parrot project aims to provide common byte code formatvirtual machineand optimization techniques for variety of programming languagesincluding python python' own pvm runs python code more efficiently than parrot (as famously demonstrated by pie challenge at software conference--search the web for details)but it' unclear how parrot will evolve in relation to python specifically see the former unladen swallow project--an open source project developed by google engineers--sought to make standard python faster by factor of at least and fast enough to replace the language in many contexts this was an optimization branch of cpython (specifically python )intended to be compatible yet faster by virtue of adding jit to standard python as write this in this project seems to have drawn to close (per its withdrawn python pepit was "going the way of the norwegian blue"stillits lessons gained may be leveraged in other formssearch the web for breaking developments although future implementation schemes may alter the runtime structure of python somewhatit seems likely that the byte code compiler will still be the standard for some time to come the portability and runtime flexibility of byte code are important features of many python systems moreoveradding type constraint declarations to support static compilation would likely break much of the flexibilityconcisenesssimplicityand overall spirit of python coding due to python' highly dynamic natureany future implementation will likely retain many artifacts of the current pvm summary this introduced the execution model of python--how python runs your programs--and explored some common variations on that modeljust-in-time compilers and the like although you don' really need to come to grips with python internals to write python scriptsa passing acquaintance with this topics will help you truly understand how your programs run once you start coding them in the next you'll start actually running some code of your own firstthoughhere' the usual quiz how python runs programs