the source file resides in the examples package per the example - listing label shown earlierthis script' full filename is pp \preview\initdata py in the examples tree we'll use these conventions throughout the booksee the preface for more on getting the examples if you wish to work along occasionally give more of the directory path in system prompts when it' useful to provide the extra execution contextespecially in the system part of the book ( " :\prefix from windows or more directory namesscript start-up pointers gave pointers for using the interactive prompt earlier now that we've started running script fileshere are also few quick startup pointers for using python scripts in generalon some platformsyou may need to type the full directory path to the python program on your machineif python isn' on your system path setting on windowsfor examplereplace python in the command with :\python \python (this assumes you're using python on most windows systems you also don' need to type python on the command line at alljust type the file' name to run itsince python is registered to open pyscript files you can also run this file inside python' standard idle gui (open the file and use the run menu in the text edit window)and in similar ways from any of the available third-party python ides ( komodoeclipsenetbeansand the wing ideif you click the program' file icon to launch it on windowsbe sure to add an input(call to the bottom of the script to keep the output window up on other systemsicon clicks may require #line at the top and executable permission via chmod command 'll assume here that you're able to run python code one way or another againif you're stucksee other books such as learning python for the full story on launching python programs data format script nowall we have to do is store all of this in-memory data in file there are variety of ways to accomplish thisone of the most basic is to write one piece of data at timewith separators between each that we can use when reloading to break the data apart example - shows one way to code this idea sneak preview