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

None of the above solutions worked for me. Ended up doing this instead:

nnoremap D :Gedith :qk