if file_exists(Directory..filename) then

        if link_exists(State, filename) then

function link_exists(State, filename)
  if State.link_cache == nil then
    State.link_cache = {}
  end
  if State.link_cache[filename] == nil then
    State.link_cache[filename] = file_exists(Directory..filename)
  end
  return State.link_cache[filename]
end

  State.link_cache = {}