How to jump to multiple items

[liketoeatcheese]

Hey mate, I have read through the docs and tried out different variance but couldn't make it work

Desire action

Remap <C-u> to jump down 4 times when there are matches
Remap <C-i> to jump up 4 times when there are matches

Documentation section

Under KEYBIND.md
<tab> -> if completion menu is open: select next item

Attempts

Here's what I have tried. I have tried different key maps other than <C-u> and <C-i> but no luck

    vim.api.nvim_set_keymap("i", "<C-u>", [[pumvisible() ? "\<C-n>\<C-n>\<C-n>\<C-n>" : "\<Tab>"]], { expr = true, silent = true })
    vim.api.nvim_set_keymap("i", "<C-i>", [[pumvisible() ? "\<C-p>\<C-p>\<C-p>\<C-p>" : "\<BS>"]], { expr = true, silent = true })