toggle option function

gistfile1.txt

nnoremap [Option] <Nop>
nmap xo [Option]
nnoremap <silent>[Option]n :<C-u>call <SID>ToggleOption('number')<CR>
nnoremap <silent>[Option]w :<C-u>call <SID>ToggleOption('wrap')<CR>
nnoremap <silent>[Option]/ :<C-u>call <SID>ToggleOption('wrapscan')<CR>
function! s:ToggleOption(option)
    if has_key(g:toggle_option_extra, a:option)
        for e in g:toggle_option_extra[a:option]
            if exists('+' . e) && eval("&" . e) == 0
                execute 'setlocal' e . '!' e . '?'
                return
            endif
        endfor
    elseif exists('+' . a:option)
        execute 'setlocal' a:option . '!' a:option . '?'
    endif
endfunction
let g:toggle_option_extra = {
\     'number' : ['number', 'relativenumber']
\ }