instance method is_non_final

# File actionmailer/lib/action_mailer/vendor/tmail-1.2.7/tmail/vendor/rchardet-1.3/lib/rchardet/hebrewprober.rb, line 178
    def is_non_final(c)
      # The normal Tsadi is not a good Non-Final letter due to words like 
      # 'lechotet' (to chat) containing an apostrophe after the tsadi. This 
      # apostrophe is converted to a space in FilterWithoutEnglishLetters causing 
      # the Non-Final tsadi to appear at an end of a word even though this is not 
      # the case in the original text.
      # The letters Pe and Kaf rarely display a related behavior of not being a 
      # good Non-Final letter. Words like 'Pop', 'Winamp' and 'Mubarak' for 
      # example legally end with a Non-Final Pe or Kaf. However, the benefit of 
      # these letters as Non-Final letters outweighs the damage since these words 
      # are quite rare.
      return [NORMAL_KAF, NORMAL_MEM, NORMAL_NUN, NORMAL_PE].include?(c)
    end