You need to specify a specific implementation of the trait in order to call the
method.

Erroneous code example:

```compile_fail,E0790
trait Coroutine {
    fn create() -> u32;
}

struct Impl;

impl Coroutine for Impl {
    fn create() -> u32 { 1 }
}

struct AnotherImpl;

impl Coroutine for AnotherImpl {
    fn create() -> u32 { 2 }
}

let cont: u32 = Coroutine::create();
// error, impossible to choose one of Coroutine trait implementation
// Should it be Impl or AnotherImpl, maybe something else?
```

This error can be solved by adding type annotations that provide the missing
information to the compiler. In this case, the solution is to use a concrete
type:

```
trait Coroutine {
    fn create() -> u32;
}

struct AnotherImpl;

impl Coroutine for AnotherImpl {
    fn create() -> u32 { 2 }
}

let gen1 = AnotherImpl::create();

// if there are multiple methods with same name (different traits)
let gen2 = <AnotherImpl as Coroutine>::create();
```