code: def __name_triplet(input_string):
      
      if input_string == '':
          # highly unlikely: no first name, like for instance some Indian persons
          # with only one name on the passport
          # pylint: disable=W0511
          return 'XXX' 
  
      consonants, vowels = __consonants_and_vowels(input_string)
      
      if len(consonants) > 3:
          return "%s%s%s" % (consonants[0], consonants[2], consonants[3])
  
      return __common_triplet(input_string, consonants, vowels)
docs: __name_triplet(input_string) -> string