fixed minor differences between 'compiled' generators and the example used. Added bonus section to prove it works

src/3_generators_pin.md

@@ -221,7 +221,6 @@ Instead of discussing it in theory, let's look at some code.
 let mut gen = move || {
         let to_borrow = String::from("Hello");
         let borrowed = &to_borrow;
-        println!("{}", borrowed);
         yield borrowed.len();
         println!("{} world!", borrowed);
     };
@@ -513,8 +512,52 @@ Hopefully, after this you'll have an idea of what happens when you use the
 `yield` or `await` keywords inside an async function, and why we need `Pin` if 
 we want to be able to safely borrow across `yield/await` points.
 
+
+## Bonus
+
+Thanks to [PR#45337][pr45337] you can actually run code like the one we display here in Rust
+today using the `static` keyword on nightly. Try it for yourself:
+
+
+```rust
+#![feature(generators, generator_trait)]
+use std::ops::{Generator, GeneratorState};
+
+
+pub fn main() {
+    let gen1 = static || {
+        let to_borrow = String::from("Hello");
+        let borrowed = &to_borrow;
+        yield borrowed.len();
+        println!("{} world!", borrowed);
+    };
+    
+    let gen2 = static || {
+        let to_borrow = String::from("Hello");
+        let borrowed = &to_borrow;
+        yield borrowed.len();
+        println!("{} world!", borrowed);
+    };
+
+    let mut pinned1 = Box::pin(gen1);
+    let mut pinned2 = Box::pin(gen2);
+
+    if let GeneratorState::Yielded(n) = pinned1.as_mut().resume() {
+        println!("Gen1 got value {}", n);
+    }
+    
+    if let GeneratorState::Yielded(n) = pinned2.as_mut().resume() {
+        println!("Gen2 got value {}", n);
+    };
+
+    let _ = pinned1.as_mut().resume();
+    let _ = pinned2.as_mut().resume();
+}
+```
+
 [rfc2033]: https://github.com/rust-lang/rfcs/blob/master/text/2033-experimental-coroutines.md
 [greenthreads]: https://cfsamson.gitbook.io/green-threads-explained-in-200-lines-of-rust/
 [rfc1823]: https://github.com/rust-lang/rfcs/pull/1823
 [rfc1832]: https://github.com/rust-lang/rfcs/pull/1832
-[optimizing-await]: https://tmandry.gitlab.io/blog/posts/optimizing-await-1/
+[optimizing-await]: https://tmandry.gitlab.io/blog/posts/optimizing-await-1/
+[pr45337]: https://github.com/rust-lang/rust/pull/45337/files