t() :: %EasyPost.Shipment{batch_id: nil | String.t, batch_message: nil | String.t, batch_status: nil | String.t, buyer_address: EasyPost.Address.t, created_at: DateTime.t, from_address: EasyPost.Address.t, id: nil | String.t, is_return: boolean, mode: EasyPost.mode, parcel: EasyPost.Parcel.t, rates: [EasyPost.Shipment.Rate.t], reference: nil | String.t, refund_status: nil | :submitted | :refunded | :rejected, return_address: EasyPost.Address.t, selected_rate: nil | EasyPost.Shipment.Rate.t, status: String.t, to_address: EasyPost.Address.t, tracking_code: nil | String.t, updated_at: DateTime.t, usps_zone: nil | String.t}