interface FreeT {}
class Pure implements FreeT {
    private $a;

    public function __construct($a) {
        $this->a = $a;
 
    }
    public function patternMatched(callable $fn) {
        return $fn($this->a);
    }
}
class Free implements FreeT {
    private $f;
private $FreeT;

    public function __construct($f,$FreeT) {
        $this->f = $f;
$this->FreeT = $FreeT;
 
    }
    public function patternMatched(callable $fn) {
        return $fn($this->f, $this->FreeT);
    }
}