Udacity Machine Learning course count words

"""Count words."""defCount_words (S, N):"""Return The n most frequently occuring words in S."""        #Todo:count The number of occurences of each word in SWord =s.split () worddict= {}     forIteminchWord:ifItem not inchWorddict:worddict[item]= 1Else: Worddict[item]+ = 1#Todo:sort the occurences in descending order (alphabetically in case of ties)Sortedworddict = sorted (Worddict.iteritems (), key =LambdaX: (-x[1],x[0]), reverse=False)#Todo:return the top n words as a list of tuples (<word>, <count>)Top_n = []     forIinchrange (N): Top_n.append (Sortedworddict[i])returnTop_ndefTest_run ():"""Test count_words () with some inputs."""    PrintCount_words ("Cat Bat Mat cat bat Cat", 3)    PrintCount_words ("Betty bought a bit of butter but the butter was bitter", 3)if __name__=='__main__': Test_run ()

Udacity Machine Learning course count words