public function testIsNaryPredicate()
 {
     $predicate = Callables::newPredicate(function ($a, $b, $c) {
         return false;
     });
     $this->assertFalse(Callables::isUnaryPredicate($predicate));
     $this->assertFalse(Callables::isBinaryPredicate($predicate));
     $this->assertTrue(Callables::isNaryPredicate($predicate));
 }