## [`DoubleEndedIterator`](https://doc.rust-lang.org/std/iter/trait.DoubleEndedIterator.html)
When deriving for enum like the following:
```rust
#[derive(DoubleEndedIterator)]
enum Enum {
A(A),
B(B),
}
```
Code like this will be generated:
```rust
enum Enum {
A(A),
B(B),
}
impl ::core::iter::DoubleEndedIterator for Enum
where
A: ::core::iter::DoubleEndedIterator,
B: ::core::iter::DoubleEndedIterator- ::Item>,
{
#[inline]
fn next_back(&mut self) -> ::core::option::Option {
match self {
Enum::A(x) => ::core::iter::DoubleEndedIterator::next_back(x),
Enum::B(x) => ::core::iter::DoubleEndedIterator::next_back(x),
}
}
}
```