finalize Function

  function finalize(self) result(error)
  !< Finalize file (writer).
  class(vtm_file), intent(inout) :: self  !< VTM file.
  integer(I4P)                   :: error !< Error status.

  error = 1
  if (allocated(self%scratch_unit)) then
     error = self%parse_scratch_files()
     deallocate(self%scratch_unit)
  endif
  if (allocated(self%xml_writer)) error = self%xml_writer%finalize()
  endfunction finalize