anchor.diff:  !
   !======================================================================>
   
  +  ! ARGUMENTS:
     CLASS(datetime),INTENT(INOUT) :: self
     INTEGER,        INTENT(IN)    :: d
   
  
positive.code: !
  !======================================================================>
  
    TYPE(datetime),INTENT(IN) :: d
  
    INTEGER :: year
  
negative.code: !
  !======================================================================>
  
    ! ARGUMENTS:
    CLASS(datetime),INTENT(IN) :: self
  
    tm%tm_sec   = self%second
  