function update_cors()
  if #corlist > 0 then
    for cor in all(corlist) do
      if costatus(cor) != 'dead' then
        coresume(cor)
      else
        del(corlist, cor)
      end
    end
  end
end

function _init()
  corlist = {}
  objlist = {}
end

function _update60()
  if #objlist > 0 then
    for o in all(objlist) do
      o:update()
    end
  end
  update_cors()
end

function _draw()
  cls()
  map()
  if #objlist > 0 then
    for o in all(objlist) do
      o:draw()
    end
  end
end