code: func (ns *Namespace) Replace(s, old, new interface{}) (string, error) {
  	ss, err := cast.ToStringE(s)
  	if err != nil {
  		return "", err
  	}
  
  	so, err := cast.ToStringE(old)
  	if err != nil {
  		return "", err
  	}
  
  	sn, err := cast.ToStringE(new)
  	if err != nil {
  		return "", err
  	}
  
  	return _strings.Replace(ss, so, sn, -1), nil
  }
docs: // Replace returns a copy of the string s with all occurrences of old replaced
  // with new.