ESMF_TimeIntervalSum Function

      function ESMF_TimeIntervalSum(timeinterval1, timeinterval2)

! !RETURN VALUE:
      type(ESMF_TimeInterval) :: ESMF_TimeIntervalSum

! !ARGUMENTS:
      type(ESMF_TimeInterval), intent(in) :: timeinterval1
      type(ESMF_TimeInterval), intent(in) :: timeinterval2

! !DESCRIPTION:
!     This method overloads the (+) operator for the {\tt ESMF\_TimeInterval}
!     class.  See "interface operator(+)" above for complete description.
!
!EOPI
      integer :: localrc

      ! check inputs
      ESMF_INIT_CHECK_SHALLOW_SHORT(ESMF_TimeIntervalGetInit,timeinterval1,localrc)
      ESMF_INIT_CHECK_SHALLOW_SHORT(ESMF_TimeIntervalGetInit,timeinterval2,localrc)

      ! invoke C to C++ entry point
      call c_ESMC_TimeIntervalSum(timeinterval1, timeinterval2, &
                                  ESMF_TimeIntervalSum)

      ! mark output as successfully initialized
      call ESMF_TimeIntervalInit(ESMF_TimeIntervalSum)

      end function ESMF_TimeIntervalSum