src/Condition/Builder.php
public function whereExists(Closure $callback, $boolean = 'and', $not = false)
    {
        $type = $not ? 'NotExists' : 'Exists';

        $this->wheres[] = compact('type', 'callback', 'boolean');

        return $this;
    }
public function whereExists(Closure $callback, $boolean = 'and', $not = false)
    {
        $type = $not ? 'NotExists' : 'Exists';

        $this->wheres[] = compact('type', 'callback', 'boolean');

        return $this;
    }
either executed directly, or inserted into a larger query.