this coroutine is almost identical to suffix_matcher()except that it filters out files whose size is not in the required rangerather than those which don' have matching suffix the pipeline we have created suffers from couple of problems one problem is that we never close any of the coroutines in this case it doesn' mattersince the program terminates once the processing is finishedbut it is probably better to get into the habit of closing coroutines when we are finished with them another problem is that potentially we could be asking the operating system (under the hoodfor different pieces of information about the same file in several parts of the pipeline--and this could be slow solution is to modify the get_files(coroutine so that it returns (filenameos stat() -tuples for each file rather than just filenamesand then pass these -tuples through the pipeline this would mean that we acquire all the relevant information just once per file you'll get the chance to solve both of these problemsand to add additional functionalityin an exercise at the end of the creating coroutines for use in pipelines requires certain reorientation of thinking howeverit can pay off handsomely in terms of flexibilityand for large data sets can help minimize the amount of data held in memory as well as potentially resulting in faster throughput examplevalid py descriptors class decorators ||in this section we combine descriptors with class decorators to create powerful mechanism for creating validated attributes up to now if we wanted to ensure that an attribute was set to only valid value we have relied on properties (or used getter and setter methodsthe disadvantage of such approaches is that we must add validating code for every attribute in every class that needs it what would be much more convenient and easier to maintainis if we could add attributes to classes with the necessary validation built in here is an example of the syntax we would like to use@valid_string("name"empty_allowed=false@valid_string("productid"empty_allowed=falseregex=re compile( "[ - ]{ }\ { }")@valid_string("category"empty_allowed=falseacceptablefrozenset(["consumables""hardware""software""media"])@valid_number("price"minimum= maximum= @valid_number("quantity"minimum= maximum= class stockitemthe os stat(function takes filename and returns named tuple with various items of information about the fileincluding its sizemodeand last modified date/time