waitForSeconds Lua function equivalent to "new WaitForSeconds()" from Unity

waitforseconds.lua

-- Heavily inspired by http://www.mohiji.org/2012/12/14/lua-coroutines/

require 'socket'

local WAITING_COROUTINES = {}
function waitForSeconds(seconds)
    local milli = seconds * 1000
    local co = coroutine.running()
    assert(co ~= nil, "Cannot wait on main thread")
    local wakeuptime = socket.gettime() * 1000 + milli
    WAITING_COROUTINES[co] = wakeuptime
    return coroutine.yield(co)
end

function wakeupWaitingCoroutines()
    local toWake = {}
    for co, wakeuptime in pairs(WAITING_COROUTINES) do
        if wakeuptime < socket.gettime() * 1000 then
            table.insert(toWake, co)
        end
    end
    for _, co in ipairs(toWake) do
        WAITING_COROUTINES[co] = nil
        coroutine.resume(co)
    end
end

-- Usage example

local co = coroutine.create(function()
    repeatEach()
end)
coroutine.resume(co)

function repeatEach()
    while true do
        print("tick")
        waitForSeconds(1)
    end
end