Execute (Setup):
  " assumes 3 registered wikis in vimrc
  let g:wiki_nr = 3

Before (Define functions):
  " change the syntax using a temporary wiki
  function! SetSyntax(vw_syn)
    if a:vw_syn ==# 'default'
      let ext = 'wiki'
    elseif a:vw_syn ==# 'markdown'
      let ext = 'md'
    elseif a:vw_syn ==# 'mediawiki'
      let ext = 'mw'
    else
      Log 'Inavlid syntax ' . a:vw_syn . ' in SetSyntax()'
      return
    endif
    let path = expand('%:p:h')
    let new_temp_wiki_settings = {'path': path,
          \ 'ext': ext,
          \ 'syntax': a:vw_syn,
          \ }
    call vimwiki#vars#add_temporary_wiki(new_temp_wiki_settings)
    call vimwiki#vars#set_bufferlocal('wiki_nr', g:wiki_nr)
    let g:wiki_nr += 1
  endfunction