code: func decodeSingleUnicodeEscape(in []byte) (rune, bool) {
  	// We need at least 6 characters total
  	if len(in) < 6 {
  		return utf8.RuneError, false
  	}
  
  	// Convert hex to decimal
  	h1, h2, h3, h4 := h2I(in[2]), h2I(in[3]), h2I(in[4]), h2I(in[5])
  	if h1 == badHex || h2 == badHex || h3 == badHex || h4 == badHex {
  		return utf8.RuneError, false
  	}
  
  	// Compose the hex digits
  	return rune(h1<<12 + h2<<8 + h3<<4 + h4), true
  }
docs: // decodeSingleUnicodeEscape decodes a single \uXXXX escape sequence. The prefix \u is assumed to be present and
  // is not checked.
  // In JSON, these escapes can either come alone or as part of "UTF16 surrogate pairs" that must be handled together.
  // This function only handles one; decodeUnicodeEscape handles this more complex case.