[E037] Error: property `Foo::$s` cannot have type `string|int|callable`
   ,-[code.php:5:16]
   |
 3 | class Foo {
   *       ^^^  
   *             
   * 
 5 |         public string|int|callable $s,
   *                ^^^^^^^^^|^^^^^^^^^ ^^  
   *                         |               
   *                         |              
   *                         `-------------- try using a different type
   * 
   * Note: `void`, `never`, and `callable` types are not allowed in properties
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