on macosopen the finder windowclick applicationsand then click mu-editor on ubuntuselect applicationsaccessories terminal and then enter python - mu the first time mu runsa select mode window will appear with options adafruit circuitpythonbbc micro:bitpygame zeroand python select python you can always change the mode later by clicking the mode button at the top of the editor window note you'll need to download mu version or later in order to install the third-party modules featured in this book as of this writingis an alpha release and is listed on the download page as separate link from the main download links starting idle this book uses mu as an editor and interactive shell howeveryou can use any number of editors for writing python code the integrated development and learning environment (idlesoftware installs along with pythonand it can serve as second editor if for some reason you can' get mu installed or working let' start idle now on windows or laterclick the start icon in the lower-left corner of your screenenter idle in the search boxand select idle (python guion macosopen the finder windowclick applicationsclick python and then click the idle icon on ubuntuselect applicationsaccessories terminal and then enter idle (you may also be able to click applications at the top of the screenselect programmingand then click idle the interactive shell when you run muthe window that appears is called the file editor window you can open the interactive shell by clicking the repl button shell is program that lets you type instructions into the computermuch like the terminal or command prompt on macos and windowsrespectively python' interactive shell lets you enter instructions for the python interpreter software to run the computer reads the instructions you enter and runs them immediately in muthe interactive shell is pane in the lower half of the window with the following textjupyter qtconsole python ( : fed oct : : [msc bit (amd )type 'copyright''creditsor 'licensefor more information introduction xxxv