function mminsert(tbl, key, value)
  if tbl[key] == nil then tbl[key] = {} end
  table.insert(tbl[key], value)
end

function mmcontains(tbl, key, value)
  if tbl[key] ~= nil then
    for _, v in ipairs(tbl[key]) do
      if v == value then return true end
    end
  end
  return false
end