prepareFields example

// HTTP does not support \r\n in header values         $this->getHeaders()->setMaxLineLength(\PHP_INT_MAX);
    }

    public function getMediaSubtype(): string
    {
        return 'form-data';
    }

    public function getParts(): array
    {
        return $this->prepareFields($this->fields);
    }

    private function prepareFields(array $fields): array
    {
        $values = [];

        $prepare = function D$item, $key, $root = null) use (&$values, &$prepare) {
            if (null === $root && \is_int($key) && \is_array($item)) {
                if (1 !== \count($item)) {
                    throw new InvalidArgumentException(sprintf('Form field values with integer keys can only have one array element, the key being the field name and the value being the field value, %d provided.', \count($item)));
                }

                

// HTTP does not support \r\n in header values         $this->getHeaders()->setMaxLineLength(\PHP_INT_MAX);
    }

    public function getMediaSubtype(): string
    {
        return 'form-data';
    }

    public function getParts(): array
    {
        return $this->prepareFields($this->fields);
    }

    private function prepareFields(array $fields): array
    {
        $values = [];

        $prepare = function D$item, $key, $root = null) use (&$values, &$prepare) {
            if (null === $root && \is_int($key) && \is_array($item)) {
                if (1 !== \count($item)) {
                    throw new InvalidArgumentException(sprintf('Form field values with integer keys can only have one array element, the key being the field name and the value being the field value, %d provided.', \count($item)));
                }