Remedy for a sleep problem my MacBook Pro late 2016 has.

wifi_sleep.lua

displaySleep = false -- Need better way to determine initial state of this variable. But it should be the truth most of the time.
systemSleep = false

function handleCaffeinateUpdates() 
  wifiPower = hs.wifi.interfaceDetails().power
  if displaySleep and systemSleep and wifiPower then
    print("Disabling WiFi before going to sleep")
    hs.wifi.setPower(false)
  elseif not displaySleep and not systemSleep and not wifiPower then
    print("Woke up - enabling wifi")
    hs.wifi.setPower(true)
  end
end

function caffeinateCallback(event) 
  if     event == hs.caffeinate.watcher.systemWillSleep then systemSleep = true
  elseif event == hs.caffeinate.watcher.systemDidWake   then systemSleep = false
  elseif event == hs.caffeinate.watcher.screensDidSleep then displaySleep = true
  elseif event == hs.caffeinate.watcher.screensDidWake  then displaySleep = false
  end
  handleCaffeinateUpdates()
end

sleepWatcher = hs.caffeinate.watcher.new(caffeinateCallback)
sleepWatcher:start()