## Keyboard shortcuts

Press `←` or `→` to navigate between chapters

Press `S` or `/` to search in the book

Press `?` to show this help

Press `Esc` to hide this help

# Error code E0751

There are both a positive and negative trait implementation for the same type.

Erroneous code example:

    #![allow(unused)]
    fn main() {
    trait MyTrait {}
    impl MyTrait for i32 { }
    impl !MyTrait for i32 { } // error!
    }

Negative implementations are a promise that the trait will never be implemented for the given types. Therefore, both cannot exist at the same time.