code: def unicode_sorter(input):
      
  
      # key1: compare words lowercase and replace umlauts according to DIN 5007
      key1 = input.lower()
      key1 = key1.replace(u"ä", u"a")
      key1 = key1.replace(u"ö", u"o")
      key1 = key1.replace(u"ü", u"u")
      key1 = key1.replace(u"ß", u"ss")
  
      # key2: sort the lowercase word before the uppercase word and sort
      # the word with umlaut after the word without umlaut
      # key2=input.swapcase()
  
      # in case two words are the same according to key1, sort the words
      # according to key2.
      return key1
docs: This function implements sort keys for the german language according to
      DIN 5007.