code: def fingerprint(self, word):
          
          word = unicode_normalize('NFKD', text_type(word.upper()))
          word = ''.join(c for c in word if c in self._letters)
  
          key = ''
  
          # add consonants in order supplied by _consonants (no duplicates)
          for char in self._consonants:
              if char in word:
                  key += char
  
          # add vowels in order they appeared in the word (no duplicates)
          for char in word:
              if char not in self._consonants and char not in key:
                  key += char
  
          return key
docs: Return the omission key.
  
          Parameters
          ----------
          word : str
              The word to transform into its omission key
  
          Returns
          -------
          str
              The omission key
  
          Examples
          --------
          >>> ok = OmissionKey()
          >>> ok.fingerprint('The quick brown fox jumped over the lazy dog.')
          'JKQXZVWYBFMGPDHCLNTREUIOA'
          >>> ok.fingerprint('Christopher')
          'PHCTSRIOE'
          >>> ok.fingerprint('Niall')
          'LNIA'