# File mconv.rb, line 227
  def encode_charset_exactly(charset)
    result = Iconv.conv(charset, Mconv.internal_mime_charset, self)
    round_trip = Iconv.conv(Mconv.internal_mime_charset, charset, result)
    if self != round_trip
      raise ArgumentError, "not round trip"
    end
    result
  end