code: func (cidr *CIDR) UnmarshalJSON(b []byte) error {
  	var s string
  	if err := json.Unmarshal(b, &s); err != nil {
  		return err
  	}
  	c, err := ParseCIDR(s)
  	if err != nil {
  		return err
  	}
  	*cidr = CIDR{c.IPNet}
  
  	return nil
  }
docs: // UnmarshalJSON unmarshals the raw JSON into the MAC address