| @@ -64,6 +64,6 @@ | ||
| 64 | 64 | function invert(callable $x): callable | 
| 65 | 65 |  { | 
| 66 | 66 |      return function ($y) use ($x): bool { | 
| 67 | - return ! $x($y); | |
| 67 | + return !$x($y); | |
| 68 | 68 | }; | 
| 69 | 69 | } |