although the specific path may be different from the one shown if written using the second formthe first python interpreter found in the shell' current environment is used the second form is more versatile because it allows for the possibility that the python interpreter is not located in /usr/bin ( it could be in /usr/local/bin or installed under $homethe shebang line is not needed (but is harmlessunder windowsall the examples in this book have shebang line of the second formalthough we won' show it note that for unix systems we assume that the name of python ' executable (or soft link to itin the path is python if this is not the caseyou will need to change the shebang line in the examples to use the correct name (or correct name and path if you use the first form)or create soft link from the python executable to the name python somewhere in the path obtaining and installing python many powerful plain text editorssuch as vim and emacscome with built-in support for editing python programs this support typically involves providing color syntax highlighting and correctly indenting or unindenting lines an alternative is to use the idle python programming environment on windows and mac os xidle is installed by default on unixes idle is built along with the python interpreter if you build from the tarballbut if you use package manageridle is usually provided as separate package as described in the introduction as the screenshot in figure showsidle has rather retro look that harks back to the days of motif on unix and windows this is because it uses the tk-based tkinter gui library (covered in rather than one of the more powerful modern gui libraries such as pygtkpyqtor wxpython the reasons for the use of tkinter are mixture of historyliberal license conditionsand the fact that tkinter is much smaller than the other gui libraries on the plus sideidle comes as standard with python and is very simple to learn and use idle provides three key facilitiesthe ability to enter python expressions and code and to see the results directly in the python shella code editor that provides python-specific color syntax highlighting and indentation supportand debugger that can be used to step through code to help identify and kill bugs the python shell is especially useful for trying out simple algorithmssnippets of codeand regular expressionsand can also be used as very powerful and flexible calculator several other python development environments are availablebut we recommend that you use idleat least at first an alternative is to create your programs in the plain text editor of your choice and debug using calls to print(it is possible to invoke the python interpreter without specifying python program if this is done the interpreter starts up in interactive mode in this mode it is possible to enter python statements and see the results exactly the same as when using idle' python shell windowand with the same