code: def filter_chars(self, chars=u""):
          
          if chars in [u"cns", u"consonants"]:
              return self.consonants
          elif chars in [u"vwl", u"vowels"]:
              return self.vowels
          elif chars in [u"cns_vwl", u"letters"]:
              return self.letters
          elif chars in [u"cns_vwl_pstr", u"cvp"]:
              return self.cns_vwl_pstr
          elif chars in [u"cns_vwl_pstr_long", u"cvpl"]:
              return self.cns_vwl_pstr_long
          elif chars in [u"cns_vwl_str", u"cvs"]:
              return self.cns_vwl_str
          elif chars in [u"cns_vwl_str_len", u"cvsl"]:
              return self.cns_vwl_str_len
          elif chars in [u"cns_vwl_str_len_wb", u"cvslw"]:
              return self.cns_vwl_str_len_wb
          elif chars in [u"cns_vwl_str_len_wb_sb", u"cvslws"]:
              return self.cns_vwl_str_len_wb_sb
          return self
docs: Return a new IPAString, containing only the IPA characters specified
          by the ``chars`` string.
  
          Valid values for ``chars`` are:
  
          * ``consonants`` or ``cns``
          * ``vowels`` or ``vwl``
          * ``letters`` or ``cns_vwl``
          * ``cns_vwl_pstr`` or ``cvp``
          * ``cns_vwl_pstr_long`` or ``cvpl``
          * ``cns_vwl_str`` or ``cvs``
          * ``cns_vwl_str_len`` or ``cvsl``
          * ``cns_vwl_str_len_wb`` or ``cvslw``
          * ``cns_vwl_str_len_wb_sb`` or ``cvslws``
  
          :rtype: IPAString