custom iterator

local t =
  {
    one =
      {
        state = "storage",
        locat = {station = 1, row = 5, collum = 3}
        prior = 3,
        descr = "This is description 1!"
      },
    two =
      {
        state = "storage",
        locat = {station = 1, row = 5, collum = 4}
        prior = 1,
        descr = "This is description 2!"
      },
    three =
      {
        state = "track",
        locat = {station = 1, row = 5, collum = 5}
        prior = 2,
        descr = "This is description 3!"
      }
  }

local function storage(t)
  local curr = 0
  local toDo = {}
  --populate toDo table
  for i, j in pairs(t) do
    if j["state"] == "storage" then
      toDo[#toDo + 1] = i
    end
  end
  table.sort(toDo)
  --iterator stuff
  return function()
    curr = curr + 1
    --stop condition
    if curr <= #toDo then
      --for loop parameters return
      return toDo[curr], t[toDo[curr]]
    else
      return nil
  end
  end
end

for name, data in storage(t) do
  print(name..": "..data["descr"])
end