public ssize_t         get_length         ();
public uchar           get_days_in_month  (DateYear year);
public bool            valid              ();
public bool            valid              ();
public static pointer  malloc             (ulong n_bytes);
public static pointer  malloc0            (ulong n_bytes);
public static pointer  realloc            (pointer mem,
                                           ulong   n_bytes);