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    <textarea name="content" rows="20" cols="80">&lt;?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier &lt;fabien@symfony.com&gt;
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Mime\Part;

use Symfony\Component\Mime\Header\Headers;

/**
 * @author Fabien Potencier &lt;fabien@symfony.com&gt;
 */
abstract class AbstractPart
{
    private $headers;

    public function __construct()
    {
        $this-&gt;headers = new Headers();
    }

    public function getHeaders(): Headers
    {
        return $this-&gt;headers;
    }

    public function getPreparedHeaders(): Headers
    {
        $headers = clone $this-&gt;headers;
        $headers-&gt;setHeaderBody('Parameterized', 'Content-Type', $this-&gt;getMediaType().'/'.$this-&gt;getMediaSubtype());

        return $headers;
    }

    public function toString(): string
    {
        return $this-&gt;getPreparedHeaders()-&gt;toString().&quot;\r\n&quot;.$this-&gt;bodyToString();
    }

    public function toIterable(): iterable
    {
        yield $this-&gt;getPreparedHeaders()-&gt;toString();
        yield &quot;\r\n&quot;;
        yield from $this-&gt;bodyToIterable();
    }

    public function asDebugString(): string
    {
        return $this-&gt;getMediaType().'/'.$this-&gt;getMediaSubtype();
    }

    abstract public function bodyToString(): string;

    abstract public function bodyToIterable(): iterable;

    abstract public function getMediaType(): string;

    abstract public function getMediaSubtype(): string;
}
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