vimtabdiff script adapted

vim -c '
   function! JJaddtotab()
           let l:buf = bufnr(\'%\')
           if g:jj_old
                   tab split
                   tabmove
           else
                   tablast
                   belowright vsplit
           endif
           exe \'b \' . l:buf
           diffthis
           normal gg
           let g:jj_old = !g:jj_old
           tabfirst
   endfunction


   " @a:000 [{file}] List of files to be diffed, interleaved old/new.
   function! JJtabdiff(...)
           let g:tabdiff_active = 1
           let g:jj_old = 1
           argdo call JJaddtotab()
           tabclose
   endfunction
   ' -c 'silent :call JJtabdiff()' aa bb cc dd