error: cannot derive `Countable` for `enum`s with explicit discriminants
 --> tests/countable/enum_discriminants.rs:6:12
  |
6 |     None = 0,
  |            ^

error: cannot derive `Countable` for `enum`s with explicit discriminants
 --> tests/countable/enum_discriminants.rs:7:20
  |
7 |     Complemented = 1,
  |                    ^