if = print('stop'elseprint(nend='countdown( - xprint 'stop xprint ncountdown( stop countdown( stop nonrecursive optionslist(range( - )[ on onlyt [print(iend='for in range( - ) list(map(lambda xprint(xend=')range( - )) didn' include generator-based solution in this exercise on the grounds of merit (and humanity!)but one is listed belowall the other techniques seem much simpler in this case-- good example of cases where generators should probably be avoided remember that generators produce no results until iteratedso we need for or yield from here (yield from works in and later only)def countdown ( )if = yield 'stopelseyield for in countdown ( - )yield generator functionrecursive +yield from countdown ( - list(countdown ( )[ 'stop'nonrecursive optionsdef countdown ()yield from range( - generator functionsimpler pre for in range()yield list(countdown ()[ list( for in range( - )[ equivalent generator expression list(range( - )[ equivalent nongenerator form computing factorials the following file shows how coded this exerciseit runs on python and xand its output on is given in string literal at the end of the file naturallythere are many possible variations on its codeits rangesfor part ivfunctions and generators