PHP DateTimeInterface interface

interface DateTimeInterface {
  
  //Constants
  const string ATOM = "Y-m-d\TH:i:sP";
  const string COOKIE = "l, d-M-Y H:i:s T";
  const string ISO8601 = "Y-m-d\TH:i:sO";
  const string RFC822 = "D, d M y H:i:s O";
  const string RFC850 = "l, d-M-y H:i:s T";
  const string RFC1036 = "D, d M y H:i:s O";
  const string RFC1123 = "D, d M Y H:i:s O";
  const string RFC7231 = "D, d M Y H:i:s \G\M\T";
  const string RFC2822 = "D, d M Y H:i:s O";
  const string RFC3339 = "Y-m-d\TH:i:sP";
  const string RFC3339_EXTENDED = "Y-m-d\TH:i:s.vP";
  const string RSS = "D, d M Y H:i:s O";
  const string W3C = "Y-m-d\TH:i:sP";
  
  //Methods
  public diff(DateTimeInterface $targetObject, 
              bool $absolute = false): DateInterval
  public format(string $format): string
  public getOffset(): int
  public getTimestamp(): int
  public getTimezone(): DateTimeZone|false
  public __wakeup(): void
}