diff --git a/lua/tabnine/binary.lua b/lua/tabnine/binary.lua
index b8c7662..fa77619 100644
--- a/lua/tabnine/binary.lua
+++ b/lua/tabnine/binary.lua
@@ -8,7 +8,7 @@ local TabnineBinary = {}
 local config = require("tabnine.config")
 
 local api_version = "4.4.223"
-local binaries_path = utils.script_path() .. "/binaries"
+local binaries_path = utils.module_dir() .. "/binaries"
 
 local function arch_and_platform()
 	local os_uname = uv.os_uname()
diff --git a/lua/tabnine/chat/binary.lua b/lua/tabnine/chat/binary.lua
index fbf9f52..fff0bd3 100644
--- a/lua/tabnine/chat/binary.lua
+++ b/lua/tabnine/chat/binary.lua
@@ -13,7 +13,7 @@ local function binary_name()
 	end
 end
 
-local binary_path = utils.script_path() .. "/../chat/target/release/" .. binary_name()
+local binary_path = utils.module_dir() .. "/chat/target/release/" .. binary_name()
 
 function ChatBinary:available()
 	return vim.fn.executable(binary_path) == 1
diff --git a/lua/tabnine/chat/init.lua b/lua/tabnine/chat/init.lua
index 3b36647..4156fb9 100644
--- a/lua/tabnine/chat/init.lua
+++ b/lua/tabnine/chat/init.lua
@@ -7,8 +7,8 @@ local config = require("tabnine.config")
 
 local M = { enabled = false }
 
-local CHAT_STATE_FILE = utils.script_path() .. "/../chat_state.json"
-local CHAT_SETTINGS_FILE = utils.script_path() .. "/../chat_settings.json"
+local CHAT_STATE_FILE = utils.module_dir() .. "/chat_state.json"
+local CHAT_SETTINGS_FILE = utils.module_dir() .. "/chat_settings.json"
 
 local chat_state = nil
 local chat_settings = nil
diff --git a/lua/tabnine/status.lua b/lua/tabnine/status.lua
index 513f651..93f0333 100644
--- a/lua/tabnine/status.lua
+++ b/lua/tabnine/status.lua
@@ -3,7 +3,7 @@ local fn = vim.fn
 local utils = require("tabnine.utils")
 
 local M = {}
-local DISABLED_FILE = utils.script_path() .. "/.disabled"
+local DISABLED_FILE = utils.module_dir() .. "/.disabled"
 local config = require("tabnine.config")
 local state = require("tabnine.state")
 local tabnine_binary = require("tabnine.binary")
diff --git a/lua/tabnine/utils.lua b/lua/tabnine/utils.lua
index af9292c..fec79fe 100644
--- a/lua/tabnine/utils.lua
+++ b/lua/tabnine/utils.lua
@@ -1,105 +1,161 @@
 local fn = vim.fn
 local api = vim.api
-
+local unpack = table.unpack or unpack
+local pack = table.pack or vim.F.pack_len
 local M = {}
-local last_changedtick = vim.b.changedtick
 
+---@param func fun(...: unknown): any the callback
+---@param delay integer delay in milliseconds
+---@return fun(...: unknown)
 function M.debounce(func, delay)
 	local timer_id
 	return function(...)
 		if timer_id then fn.timer_stop(timer_id) end
-		local args = { ... }
+		local args = pack(...)
 		timer_id = fn.timer_start(delay, function()
-			func(unpack(args))
+			return func(unpack(args, 1, args.n))
 		end)
 	end
 end
 
+---@param str string
+---@return string[]
 function M.str_to_lines(str)
 	return fn.split(str, "\n")
 end
 
+---@param lines string[]
+---@return string
 function M.lines_to_str(lines)
 	return fn.join(lines, "\n")
 end
 
+---@param str string
+---@param suffix string
+---@return string
 function M.remove_matching_suffix(str, suffix)
 	if not M.ends_with(str, suffix) then return str end
 	return str:sub(1, -#suffix - 1)
 end
 
+---@param str string
+---@param prefix string
+---@return string
 function M.remove_matching_prefix(str, prefix)
 	if not M.starts_with(str, prefix) then return str end
 	return str:sub(#prefix)
 end
 
+---@generic T
+---@param tbl T[] | {n?: integer} The table to get a subset from
+---@param from integer? defaults to 1
+---@param to integer? defaults to tbl.n or #tbl.
+---@return T[]
 function M.subset(tbl, from, to)
+	to = to or tbl.n or #tbl -- support table.pack values if no end given
+	-- We can't use table.pack here because nvim_buf_set_extmark will error if non-integer keys are present
+	-- Ideally, implementations would ignore string keys in an 'array'.
 	return { unpack(tbl, from, to) }
 end
 
-function M.script_path()
+---returns the directory of the running script
+---@return string
+function M.script_dir()
 	local str = debug.getinfo(2, "S").source:sub(2)
-	return str:match("(.*/)") .. "../.."
+	return str:match("(.*/)") or "./"
+end
+
+---returns the directory of the root of the module
+---@return string
+function M.module_dir()
+	-- HACK: This only works if this file is not moved!
+	return M.script_dir() .. "../.."
 end
 
-function M.prequire(...)
-	local status, lib = pcall(require, ...)
+---pcall require. Returns nil if the module is not found.
+---Note: use @module to manage types.
+---@param modname string
+---@return unknown?
+function M.prequire(modname)
+	local status, lib = pcall(require, modname)
 	if status then return lib end
 	return nil
 end
 
+---@return boolean
 function M.pumvisible()
 	local cmp = M.prequire("cmp")
-	if cmp then
-		return cmp.visible()
-	else
-		return vim.fn.pumvisible() > 0
-	end
+	if cmp then return cmp.visible() end
+	return vim.fn.pumvisible() > 0
 end
 
+---Return the position of the cursor
+---@return number line, number column
 function M.current_position()
-	return { fn.line("."), fn.col(".") }
+	---@diagnostic disable-next-line: return-type-mismatch -- This is fine, they return non-nil values
+	return fn.line("."), fn.col(".")
 end
 
+---Returns true if str ends with suffix.
+---@param str string
+---@param suffix string
+---@return boolean
 function M.ends_with(str, suffix)
-	if str == "" then return true end
-
 	return str:sub(-#suffix) == suffix
 end
 
+---Returns true if str starts with prefix.
+---@param str string
+---@param prefix string
+---@return boolean
 function M.starts_with(str, prefix)
-	if str == "" then return true end
-
 	return str:sub(1, #prefix) == prefix
 end
 
+---Returns true if the current cursor position is the end of the current line
+---@return boolean
 function M.is_end_of_line()
 	return fn.col(".") == fn.col("$")
 end
 
+---Returns the text after the current cursor position to the end of the current line
+---@return string
 function M.end_of_line()
 	return api.nvim_buf_get_text(0, fn.line(".") - 1, fn.col(".") - 1, fn.line(".") - 1, fn.col("$"), {})[1]
 end
 
-function M.document_changed()
-	local current_changedtick = last_changedtick
-	last_changedtick = vim.b.changedtick
-	return last_changedtick > current_changedtick
+do
+	---The last time we checked for a document change
+	local last_changedtick = vim.b.changedtick
+	---Returns true if the document has changed since the last call
+	---@return boolean
+	function M.document_changed()
+		local current_changedtick = last_changedtick
+		last_changedtick = vim.b.changedtick
+		return last_changedtick > current_changedtick
+	end
 end
 
+---Returns the currently selected text. If no in visual mode, returns the empty string.
+---@return string
 function M.selected_text()
-	local mode = vim.fn.mode()
+	local mode = vim.fn.mode() ---@type string
 	if mode ~= "v" and mode ~= "V" and mode ~= "" then return "" end
-	local a_orig = vim.fn.getreg("a")
+	local a_orig = vim.fn.getreg("a", 1)
 	vim.cmd([[silent! normal! "aygv]])
-	local text = vim.fn.getreg("a")
+	---@diagnostic disable-next-line: assign-type-mismatch -- This is fine. it returns a string
+	local text = vim.fn.getreg("a") ---@type string
 	vim.fn.setreg("a", a_orig)
 	return text
 end
 
+---gets the unique values from the array
+---@generic T
+---@param array T[]
+---@return T[]
 function M.set(array)
-	local set = {}
-	local uniqueValues = {}
+	local set = {} ---@type table<unknown, true>
+	local uniqueValues = {} ---@type unknown[]
 
 	for _, value in ipairs(array) do
 		if not set[value] then
@@ -111,39 +167,17 @@ function M.set(array)
 	return uniqueValues
 end
 
-function M.select_range(range)
-	local start_row, start_col, end_row, end_col = range[1][1], range[1][2], range[2][1], range[2][2]
-
-	local v_table = { charwise = "v", linewise = "V", blockwise = "<C-v>" }
-	selection_mode = selection_mode or "charwise"
-
-	-- Normalise selection_mode
-	if vim.tbl_contains(vim.tbl_keys(v_table), selection_mode) then selection_mode = v_table[selection_mode] end
-
-	-- enter visual mode if normal or operator-pending (no) mode
-	-- Why? According to https://learnvimscriptthehardway.stevelosh.com/chapters/15.html
-	--   If your operator-pending mapping ends with some text visually selected, Vim will operate on that text.
-	--   Otherwise, Vim will operate on the text between the original cursor position and the new position.
-	local mode = api.nvim_get_mode()
-	if mode.mode ~= selection_mode then
-		-- Call to `nvim_replace_termcodes()` is needed for sending appropriate command to enter blockwise mode
-		selection_mode = vim.api.nvim_replace_termcodes(selection_mode, true, true, true)
-		api.nvim_cmd({ cmd = "normal", bang = true, args = { selection_mode } }, {})
-	end
-
-	api.nvim_win_set_cursor(0, { start_row, start_col - 1 })
-	vim.cmd("normal! o")
-	api.nvim_win_set_cursor(0, { end_row, end_col - 1 })
-end
-
-function M.select_range(range)
+---Selects a given range of text
+---@param range table
+---@param selection_mode? 'charwise'|'linewise'|'blockwise'|'v'|'V'|'<C-v>'
+function M.select_range(range, selection_mode)
 	local start_row, start_col, end_row, end_col = range[1][1], range[1][2], range[2][1], range[2][2]
 
 	local v_table = { charwise = "v", linewise = "V", blockwise = "<C-v>" }
 	selection_mode = selection_mode or "charwise"
 
 	-- Normalise selection_mode
-	if vim.tbl_contains(vim.tbl_keys(v_table), selection_mode) then selection_mode = v_table[selection_mode] end
+	selection_mode = v_table[selection_mode] or selection_mode
 
 	-- enter visual mode if normal or operator-pending (no) mode
 	-- Why? According to https://learnvimscriptthehardway.stevelosh.com/chapters/15.html