Check if struct implements a specific trait

example.rs

```rs
// Based on: https://www.reddit.com/r/rust/comments/ehr8ct/announcing_impls_a_macro_to_determine_if_a_type/

// trait for T
trait TTrate {
    const VALUE: bool = false;
}
impl<T> TTrate for T {}

// custom trait
trait MyTrait {}
impl MyTrait for Vec<u32> {}

// example structure
struct Example<T>(std::marker::PhantomData<T>);
impl<T: MyTrait> Example<T> {
    const VALUE: bool = true;
}

// run
fn main() {
    println!("Implements MyTrait?");
    println!("=> {}", Example::<u32>::VALUE);
    println!("=> {}", Example::<Vec<u32>>::VALUE);
}
```