let add_tez : tez = 21mutez + 0.000_021tez
let sub_tez : tez = 0.000021tez - 0.000_020tez
let not_enough_tez : tez = 461_168_601_842_738_7903mutez

let add_more_tez : tez =
  100tez + 10tez + 1tez + 0.1tez + 0.01tez + 0.001tez
