Book: fixed syntax coloring

Author: royalstream

src/doc/book/closures.md

@@ -322,7 +322,7 @@ to our closure when we pass it to `call_with_one`, so we use `&||`.
 A quick note about closures that use explicit lifetimes. Sometimes you might have a closure
 that takes a reference like so:
 
-```
+```rust
 fn call_with_ref<F>(some_closure:F) -> i32
     where F: Fn(&i32) -> i32 {
 
@@ -334,8 +334,8 @@ fn call_with_ref<F>(some_closure:F) -> i32
 Normally you can specify the lifetime of the parameter to our closure. We
 could annotate it on the function declaration:
 
-```ignore
-fn call_with_ref<'a, F>(some_closure:F) -> i32 
+```rust,ignore
+fn call_with_ref<'a, F>(some_closure:F) -> i32
     where F: Fn(&'a 32) -> i32 {
 ```
 
@@ -353,11 +353,11 @@ fn call_with_ref<F>(some_closure:F) -> i32
     where F: for<'a> Fn(&'a 32) -> i32 {
 ```
 
-This lets the Rust compiler find the minimum lifetime to invoke our closure and 
+This lets the Rust compiler find the minimum lifetime to invoke our closure and
 satisfy the borrow checker's rules. Our function then compiles and excutes as we
 expect.
 
-```
+```rust
 fn call_with_ref<F>(some_closure:F) -> i32
     where F: for<'a> Fn(&'a i32) -> i32 {