notes in python module called cpickle contains implementation of functions in the pickle module it is significantly faster than picklebut is restricted in that it doesn' allow subclassing of the pickler and unpickler objects python has support module that also contains implementationbut it is used more transparently (pickle takes advantage of it automatically as appropriaten the data format used by pickle is python-specific and shouldn' be assumed to be compatible with any external standards such as xml whenever possiblethe pickle module should be used instead of the marshal module because pickle is more flexiblethe data encoding is documentedand additional error-checking is performed due to security concernsprograms should not unpickle data received from untrusted sources use of the pickle module with types defined in extension modules is much more involved than what is described here implementers of extension types should consult the online documentation for details concerning the low-level protocol required to make these objects work with pickle--in particulardetails on how to implement the _reduce_ (and _reduce_ex_ (special methods that pickle uses to create the serialized byte sequences sys the sys module contains variables and functions that pertain to the operation of the interpreter and its environment variables the following variables are defined api_version an integer representing the api version of the python interpreter used when working with extension modules argv list of command-line options passed to program argv[ is the name of the program builtin_module_names tuple containing names of modules built into the python executable byteorder native byte-ordering of the machine--'littlefor little-endian or 'bigfor bigendian lib fl ff