How to use a roblox library / modules?

In roblox, or Lua 5.1 for that matter, a library(or module script if using roblox) is essentially used through a require(), which is equivalent to #include in some programming languages. Essentially here's how it works, when you run require(ModuleScriptHere), it outputs the table(or any value if you really want...) that it returns at the bottom. If we consider this as just a normal table, it proves as a useful tool for storing large arrays of data, especially ones with thousands of elements in it. Normally this itself is useful, but the real value of this is the fact that one can actually store functions inside a table as well, which one can them call on by requiring the table where they are stored. Essentially, you'd have a table within a module script, such as local FunctionThingaroos = {}. If you do function FunctionThingaroos.Whatever() and define a function below, it essentially allows you to call upon it from the table you required. Here's a quick example:

Module Script:

local FunctionThings = {}

function FunctionThings.DoWhatever()
	--Run code
end

return FunctionThings

Server Script(or local script):

local ModuleToUse = require(ModuleScriptFromBefore)

ModuleToUse.DoWhatever() -- Runs the code inside FunctionThings.DoWhatever()