const
     string
     DateTimeInterface::ATOM
      = "Y-m-d\TH:i:sP"
    ;
     const
     string
     DateTimeInterface::COOKIE
      = "l, d-M-Y H:i:s T"
    ;
     const
     string
     DateTimeInterface::ISO8601
      = "Y-m-d\TH:i:sO"
    ;
     const
     string
     DateTimeInterface::RFC822
      = "D, d M y H:i:s O"
    ;
     const
     string
     DateTimeInterface::RFC850
      = "l, d-M-y H:i:s T"
    ;
     const
     string
     DateTimeInterface::RFC1036
      = "D, d M y H:i:s O"
    ;
     const
     string
     DateTimeInterface::RFC1123
      = "D, d M Y H:i:s O"
    ;
      const
      string
      DateTimeInterface::RFC7231
       = "D, d M Y H:i:s \G\M\T"
    ;
     const
     string
     DateTimeInterface::RFC2822
      = "D, d M Y H:i:s O"
    ;
     const
     string
     DateTimeInterface::RFC3339
      = "Y-m-d\TH:i:sP"
    ;
     const
     string
     DateTimeInterface::RFC3339_EXTENDED
      = "Y-m-d\TH:i:s.vP"
    ;
     const
     string
     DateTimeInterface::RSS
      = "D, d M Y H:i:s O"
    ;
     const
     string
     DateTimeInterface::W3C
      = "Y-m-d\TH:i:sP"
    ;
    
    
    
    
   public format
    ( 
string $format
   ) : 
string 
   }