public function beforeTraverse(array $nodes)
    {
        if (!$this->atLeastPhp7) {
            return; // @codeCoverageIgnore
        }

        $prependStrictTypes = $this->strictTypes;

        foreach ($nodes as $key => $node) {
            if ($node instanceof Declare_) {
                foreach ($node->declares as $declare) {
                    // For PHP Parser 4.x
                    $declareKey = $declare->key instanceof Identifier ? $declare->key->toString() : $declare->key;
                    if ($declareKey === 'strict_types') {
                        $value = $declare->value;
                        if (!$value instanceof LNumber || ($value->value !== 0 && $value->value !== 1)) {
                            throw new FatalErrorException(self::EXCEPTION_MESSAGE, 0, E_ERROR, null, $node->getLine());
                        }

                        $this->strictTypes = $value->value === 1;
                    }
                }
            }
        }

        if ($prependStrictTypes) {
            $first = \reset($nodes);
            if (!$first instanceof Declare_) {
                $declare = new Declare_([new DeclareDeclare('strict_types', new LNumber(1))]);
                \array_unshift($nodes, $declare);
            }
        }

        return $nodes;
    }