lua code for a mod that works for 1 based numbers

mod.lua

--[[
saw this buried in this code
https://www.lexaloffle.com/bbs/?tid=49068
]]--

function mod(val,modulo)
  --Mod for 1 based numbers.
  --3%3=3. 4%3=1, 1%3=1
  return (val-1)%modulo+1
end