via (https://www.linux.com/learn/tutorials/442438-vim-tips-folding-fun)
zf#j
creates a fold from the cursor down # lines.zf/string
creates a fold from the cursor to string .zj
moves the cursor to the next fold.zk
moves the cursor to the previous fold.zo
opens a fold at the cursor.zO
opens all folds at the cursor.zm
increases the foldlevel by one.zM
closes all open folds.