string formatting expression ('part% 'to make sure that filenames all have the same number of digits at the end (fourwhen sortedthe leading zero characters in small numbers guarantee that part files are ordered for joining correctly alternativelywe could strip off digits in filenamesconvert them with intand sort numericallyby using the list sort method' keys argumentbut that would still imply that all filenames must start with the some type of substringand so doesn' quite remove the file-naming dependency between the split and join scripts because these scripts are designed to be two steps of the same processthoughsome dependencies between them seem reasonable usage variations finallylet' run few more experiments with these python system utilities to demonstrate other usage modes when run without full command-line argumentsboth split and join are smart enough to input their parameters interactively here they are chopping and gluing the python self-installer file on windows againwith parameters typed in the dos console windowc:\temppython :\pp \system\filetools\split py file to be splitpython- msi directory to store part filessplitout splitting :\temp\python- msi to :\temp\splitout by split finished parts are in :\temp\splitout press enter key :\temppython :\pp \system\filetools\join py directory containing part filessplitout name of file to be recreatednewpy msi joining :\temp\splitout to make :\temp\newpy msi join completesee :\temp\newpy msi press enter key :\tempfc / python- msi newpy msi comparing files python- msi and newpy msi fcno differences encountered when these program files are double-clicked in windows file explorer guithey work the same way (there are usually no command-line arguments when they are launched this wayin this modeabsolute path displays help clarify where files really are rememberthe current working directory is the script' home directory when clicked like thisso simple name actually maps to source code directorytype full path to make the split files show up somewhere else[in pop-up dos console box when split py is clickedfile to be splitc:\temp\python- msi directory to store part filesc:\temp\parts splitting :\temp\python- msi to :\temp\parts by split finished parts are in :\temp\parts press enter key splitting and joining files