anchor.diff:  
   
   
  -!======================================================================>
  -!
  -! FUNCTION: int2str
  -!
  -! DESCRIPTION: Converts an integer i into a character string of 
  -! requested length, by pre-pending zeros if necessary.
  -!
  -!======================================================================>
   PURE FUNCTION int2str(i,length)
  +!======================================================================>
  +!
  +! Converts an integer i into a character string of requested length, 
  +! by pre-pending zeros if necessary.
  +!
  +!======================================================================>
   
     INTEGER,INTENT(IN)    :: i,length
     CHARACTER(LEN=length) :: int2str
  
positive.code: 
  
  
  !======================================================================>
  !
  ! FUNCTION: datetime_minus_datetime
  !
  ! DESCRIPTION: Subtracts a datetime instance from another datetime 
  ! instance. Returns a timedelta instance. Overloads the operator -.
  !
  !======================================================================>
  PURE ELEMENTAL FUNCTION datetime_minus_datetime(d0,d1) RESULT(t)
  
    TYPE(datetime),INTENT(IN) :: d0,d1
    TYPE(timedelta)           :: t
  
negative.code: 
  
  
  PURE ELEMENTAL INTEGER FUNCTION weekday(self)
  !======================================================================>
  !
  ! datetime-bound method to calculate day of the week using
  ! Zeller's congruence. Returns an integer scalar in the range of [0-6], 
  ! starting from Sunday.
  !
  !======================================================================>
  
    CLASS(datetime),INTENT(IN) :: self
  
  