How do you exit vimdiff mode in vim, specifically, for Fugitive?

Question

I am using vim with the fugitive extension. It has a :Gdiff command which brings you into vimdiff mode, but what is the right/quick way to close/quit vimdiff mode?

I.e.,

Answer 1

Yet another way. What I have in fugitive.vim - first save some info (s:gitbufname) when diff starts:

function! s:Diff(vert,...) abort
  call sy#toggle()
  let s:startcol = winwidth(0)
  let &columns=(winwidth(0) * 2 - 20)
...
    if getwinvar('#', '&diff')
      let s:gitbufname = bufname("%")
      wincmd p
      call feedkeys(winnr."\w", 'n')
    endif
...
endfunction

and later when leaving the buffer switch window to the saved buffer and restore:

augroup fugitive_diff
autocmd!
autocmd BufWinLeave *
  \ if s:can_diffoff(+expand('')) && s:diff_window_count() == 2 |
  \   if exists('s:gitbufname') && winnr() != bufwinnr(s:gitbufname) |
  \     let nr = bufnr("%") | exe bufwinnr(s:gitbufname).'wincmd w' | exe 'buf'.nr |
  \   endif |
  \   call s:diffoff_all(getbufvar(+expand(''), 'git_dir')) |
  \   call sy#toggle() |
  \   call airline#load_theme() | call airline#update_statusline() |
  \   let &columns=s:startcol |
  \ endif
...