and the last section showed how to combine class decorators with descriptors to provide powerful and flexible mechanism for creating validated attributes this completes our coverage of the python language itself not every feature of the language has been covered here and in the previous but those that have not are obscure and rarely used none of the subsequent introduces new language featuresalthough all of them make use of modules from the standard library that have not been covered beforeand some of them take techniques shown in this and earlier further than we have seen so far furthermorethe programs shown in the following have none of the constraints that have applied previously ( to only use aspects of the language that had been covered up to the point they were introduced)so they are the book' most idiomatic examples exercises ||none of the first three exercises described here requires writing lot of code-although the fourth one does--and none of them are easy copy the magic-numbers py program and delete its get_function(functionsand all but one of its load_modules(functions add getfunction functor class that has two cachesone to hold functions that have been found and one to hold functions that could not be found (to avoid repeatedly looking for function in module that does not have the functionthe only modifications to main(are to add get_function getfunction(before the loopand to use with statement to avoid the need for finally block alsocheck that the module functions are callable using collections callable rather than using hasattr(the class can be written in about twenty lines solution is in magic-numbers_ans py create new module file and in it define three functionsis_ascii(that returns true if all the characters in the given string have code points less than is_ascii_punctuation(that returns true if all the characters are in the string punctuation stringand is_ascii_printable(that returns true if all the characters are in the string printable string the last two are structurally the same each function should be created using lambda and can be done in one or two lines using functional-style code be sure to add docstring for each one with doctests and to make the module run the doctests the functions require only three to five lines for all three of themwith the whole module fewer than lines including doctests solution is given in ascii py create new module file and in it define the atomic context manager class this class should work like the atomiclist class shown in this except that instead of working only with lists it should work with any mutable collection type the __init__(method should check the suitability