public function optimizeNot($expr, CompilationContext $compilationContext)
    {
        /*
         * Compile the expression negating the evaluated expression
         */
        if ('not' == $expr['type']) {
            $conditions = $this->optimize($expr['left'], $compilationContext);
            if (false !== $conditions) {
                if (null !== $this->unreachable) {
                    $this->unreachable = !$this->unreachable;
                }
                if (null !== $this->unreachableElse) {
                    $this->unreachableElse = !$this->unreachableElse;
                }

                return '!('.$conditions.')';
            }
        }

        return false;
    }