code: func escape(cis model.CIStr, sqlMode mysql.SQLMode) string {
  	var quote string
  	if sqlMode&mysql.ModeANSIQuotes != 0 {
  		quote = `"`
  	} else {
  		quote = "`"
  	}
  	return quote + strings.Replace(cis.O, quote, quote+quote, -1) + quote
  }
docs: // escape the identifier for pretty-printing.
  // For instance, the identifier "foo `bar`" will become "`foo ``bar```".
  // The sqlMode controls whether to escape with backquotes (`) or double quotes
  // (`"`) depending on whether mysql.ModeANSIQuotes is enabled.