code: func isInCharacterRange(r rune) (inrange bool) {
  	return r == 0x09 ||
  		r == 0x0A ||
  		r == 0x0D ||
  		r >= 0x20 && r <= 0xDF77 ||
  		r >= 0xE000 && r <= 0xFFFD ||
  		r >= 0x10000 && r <= 0x10FFFF
  }
docs: // Decide whether the given rune is in the XML Character Range, per
  // the Char production of http://www.xml.com/axml/testaxml.htm,
  // Section 2.2 Characters.