# File escape.rb, line 394
  def rfc2822_quoted_string(str)
    if /\A(?:#{RFC2822_FWS}?[\x01-\x09\x0b\x0c\x0e-\x7f])*#{RFC2822_FWS}?\z/o !~ str
      raise ArgumentError, "not representable in quoted-string of RFC 2822: #{str.inspect}"
    end
    s = '"' + str.gsub(/["\\]/, '\\\\\&') + '"'
    MIMEParameter.new_no_dup(s)
  end