Vim folding commands
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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.
za toggle a fold at the cursor.
zo opens a fold at the cursor.
zO opens all folds at the cursor.
zc closes a fold under cursor. 
zm increases the foldlevel by one.
zM closes all open folds.
zr decreases the foldlevel by one.
zR decreases the foldlevel to zero -- all folds will be open.
zd deletes the fold at the cursor.
zE deletes all folds.
[z move to start of open fold.
]z move to end of open fold.

资料来源：vim docs