code: def cns_vwl_str_len_wb_sb(self):
          
          return IPAString(ipa_chars=[c for c in self.ipa_chars if (c.is_letter) or (c.is_suprasegmental and (c.is_stress or c.is_length or c.is_word_break or c.is_syllable_break))])
docs: Return a new IPAString, containing only:
          
          1. the consonants,
          2. the vowels, and
          3. the stress diacritics,
          4. the length diacritics,
          5. the word breaks, and
          6. the syllable breaks
  
          in the current string.
  
          :rtype: IPAString