editing if you want an illustrationyou might try changing adder cgimaking an error like impor cgiand try using adder html with the flawed script (then fix it and try again if you find it in idleyou can jump to the line where the error was detected execution errors the error trace for execution errors is displayed in your web browserthanks to the final boilerplate code with the try-catch block at the end of the cgi script if you omit that final boilerplate codeyou completely lose descriptive feedbackbe sure to include that boilerplate codeyou can also see an illustration now get an error by introducing the statementbad 'aappend(' 'in the main function and run it (then take it out server errors your work can cause an issue inside the local servernot directly in the python execution some errors are communicated to the browserbut not necessarily all other errors appear in the log generated in the local server' window you could have file named wrongfor instancein any operating system alsoon mac or in linuxwhere the cgi script needs to be set as executablean error with non-executable cgi script only shows up in this log in the local server window you should be able to fix this error by running the cgifix py programin the same folder logical errors since your output appears in the web browserwhen you produced something legal but other than what you intendedyou see it in the browser if it is formatting errorfix your output page template if you get wrong answerscheck your processinput function here is an outline for client/server program testingemphasizing errors to be conscious of and avoid if you have problemsplease actively check out this whole listyou are encouraged to add your files into the examples www folder if you really want to work in different folderyou will want to copy number of support files into that foldercgifix py and localcgiserver,pyplus dumpcgi cgi if you want to test web forms separately for windowsstartserver cmd on mac be sure to run cgifix pyto generate the folder-specific version of cgiserverscript if you want an easy environment to test fancy processinput functionembed it in regular python programas we have discussed for web py programs then you can test it normally in idle this will also allow you to make sure the web templatethat you refer to in your processinput functionis in legitimate formwith substitutions only for local variables you can code cgi script in idlebut not run it be sure to save it with the suffix cginot py do not run it it idle the only testing you can do in idle is for syntaxusing the menu sequence run -check module or its keyboard shortcut do run that test at the end of your cgi scriptmake sure you include the boilerplate code that catches execution errors remember to run cgifix py in the same folder as precaution to clean things upparticularly with new file on mac make sure your local server is goingand that all the files you reference are in the same folder as the local server make sure you test your page by starting it in your web browser with url starting will not cause an obvious error the dynamic actions will just not take place if you are not paying attentionthis can happen and be very confusingif things do not workremember the three places to check for errors after initially checking for syntax errors in idlethe remaining errors might be displayed on the output page in the browser (if you confirmed that you have the try-catch boilerplate code at the endif that does not totally explain thingsremember to check the server console windowtoo we have not covered web forms yetbut rather than bite off too much at oncethis is good time to write your own first cgi script in the following exercise cgi dynamic web pages