"foo is not None" fails on all languages except Julia
`None` is mapped to `Option` on rust, resulting in
```rust
error[E0308]: mismatched types
 --> none.rs:3:15
  |
3 |     if var != None {
  |               ^^^^ expected `i32`, found enum `Option`
  |
  = note: expected type `i32`
             found enum `Option<_>`
```
If this mapping of `None` to `Option` has some positive effect, we need a test case for those good scenarios.

Dart:
```
cases/none.dart:7:15: Error: Getter not found: 'None'.
  if (var_ != None) {
              ^^^^
```
Go:
> cases/none.go:9:13: undefined: None

Kotlin:
> cases/none.kt:3:17: error: unresolved reference: None

Nim:
> tests/cases/none.nim(2, 7) Error: invalid token: trailing underscore