dictionary iterators--iterators do not sort always use parentheses to call function you must add parentheses after function name to call itwhether it takes arguments or not ( use function()not functionin the next part of this bookwe'll learn that functions are simply objects that have special operation-- call that you trigger with the parentheses they can be referenced like any other object without triggering call in classesthis problem seems to occur most often with filesit' common to see beginners type file close to close filerather than file close(because it' legal to reference function without calling itthe first version with no parentheses succeeds silentlybut it does not close the filedon' use extensions or paths in imports and reloads omit directory paths and file extensions in import statements--say import modnot import mod py we discussed module basics in and will continue studying modules in part because modules may have other extensions besides py pycfor instance)hardcoding particular extension is not only illegal syntaxit doesn' make sense python picks an extension automaticallyand any platform-specific directory path syntax comes from module search path settingsnot the import statement and other pitfalls in other parts be sure to also see the built-in type warnings at the end of the prior partas they may qualify as coding issues too there are additional "gotchasthat crop up commonly in python coding--losing built-in function by reassigning its namehiding library module by using its name for one of your ownchanging mutable argument defaultsand so on--but we don' have enough background to cover them yet to learn more about both what you should and shouldn' do in pythonyou'll have to read onlater parts extend the set of "gotchasand fixes we've added to here summary this took us on tour of program documentation--both documentation we write ourselves for our own programsand documentation available for tools we use we met docstringsexplored the online and manual resources for python referenceand learned how pydoc' help function and web page interfaces provide extra sources of documentation because this is the last in this part of the bookwe also reviewed common coding mistakes to help you avoid them in the next part of this bookwe'll start applying what we already know to larger program constructs specificallythe next part takes up the topic of functions-- tool used to group statements for reuse before moving onhoweverbe sure to work through the set of lab exercises for this part of the book that appear at the end of this and even before thatlet' run through this quiz summary