declare namespace Ledger {
  interface User {
    id?: number
    key: string
    balance: number
    addition_count: number
    consumption_count: number
    first_entry: Date
    last_entry: Date
  }

  namespace User {
    type Response = {
      history?: Ledger.Entry[]
      entry_count?: number
      balance?: number
    } | null
  }
}