# File lib/mail/version_specific/ruby_1_9.rb, line 39
    def Ruby19.b_value_decode(str)
      match = str.match(/\=\?(.+)?\?[Bb]\?(.+)?\?\=/m)
      if match
        encoding = match[1]
        str = Ruby19.decode_base64(match[2])
        str.force_encoding(encoding)
      end
      str
    end