@type t() :: %ExOanda.TransferFundsTransaction{
  account_balance: float() | nil,
  account_id: String.t() | nil,
  amount: float() | nil,
  batch_id: String.t() | nil,
  comment: String.t() | nil,
  funding_reason: String.t() | nil,
  id: String.t() | nil,
  request_id: String.t() | nil,
  time: DateTime.t() | nil,
  type: ExOanda.Type.Atom.t() | nil,
  user_id: integer() | nil
}