code: func (ip *Checker) Contains(addr string) (bool, error) {
  	if len(addr) == 0 {
  		return false, errors.New("empty IP address")
  	}
  
  	ipAddr, err := parseIP(addr)
  	if err != nil {
  		return false, fmt.Errorf("unable to parse address: %s: %s", addr, err)
  	}
  
  	return ip.ContainsIP(ipAddr), nil
  }
docs: // Contains checks if provided address is in the trusted IPs