code: func escapeStr(s string, charsToEscape string) string {
  	var ret string
  	for _, currRune := range s {
  		appended := false
  		for _, escapableRune := range charsToEscape {
  			if currRune == escapableRune {
  				ret += `\` + string(currRune)
  				appended = true
  				break
  			}
  		}
  		if !appended {
  			ret += string(currRune)
  		}
  	}
  	return ret
  }
docs: // escapeStr returns s with every rune in charsToEscape escaped by a backslash