# File lib/active_support/core_ext/uri.rb, line 13
      def unescape(str, escaped = /%[a-fA-F\d]{2}/)
        # TODO: Are we actually sure that ASCII == UTF-8?
        # YK: My initial experiments say yes, but let's be sure please
        enc = str.encoding
        enc = Encoding::UTF_8 if enc == Encoding::US_ASCII
        str.gsub(escaped) { [$&[1, 2].hex].pack('C') }.force_encoding(enc)
      end