vim.o.foldcolumn = "auto:9" -- '0' is not bad
vim.o.foldlevel = 99 -- Using ufo provider need a large value, feel free to decrease the value
vim.o.foldlevelstart = 99
vim.o.foldenable = true
vim.o.fillchars = [[eob: ,fold: ,foldopen:󰅀,foldsep:│,foldclose:󰅂]]

-- Using ufo provider need remap `zR` and `zM`. If Neovim is 0.6.1, remap yourself
vim.keymap.set('n', 'zR', require('ufo').openAllFolds)
vim.keymap.set('n', 'zM', require('ufo').closeAllFolds)

-- Option 3: treesitter as a main provider instead
-- (Note: the `nvim-treesitter` plugin is *not* needed.)
-- ufo uses the same query files for folding (queries/<lang>/folds.scm)
-- performance and stability are better than `foldmethod=nvim_treesitter#foldexpr()`
require('ufo').setup({
    provider_selector = function(bufnr, filetype, buftype)
        return {'treesitter', 'indent'}
    end
})