clippy refactoring

examples/reuse_scope.rs

@@ -5,7 +5,7 @@ fn main() {
     let mut engine = Engine::new();
     let mut scope: Scope = Vec::new();
 
-    if let Ok(_) = engine.eval_with_scope::<()>(&mut scope, "let x = 4 + 5") { } else { assert!(false); }
+    if !engine.eval_with_scope::<()>(&mut scope, "let x = 4 + 5").is_ok() { assert!(false); }
 
     if let Ok(result) = engine.eval_with_scope::<i64>(&mut scope, "x") {
        println!("result: {}", result);