<form method="POST">
    <h3>Editing: post-author.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php
/**
 * Server-side rendering of the `core/post-author` block.
 *
 * @package WordPress
 */

/**
 * Renders the `core/post-author` block on the server.
 *
 * @since 5.9.0
 *
 * @param  array    $attributes Block attributes.
 * @param  string   $content    Block default content.
 * @param  WP_Block $block      Block instance.
 * @return string Returns the rendered author block.
 */
function render_block_core_post_author( $attributes, $content, $block ) {
	if ( ! isset( $block-&gt;context['postId'] ) ) {
		$author_id = get_query_var( 'author' );
	} else {
		$author_id = get_post_field( 'post_author', $block-&gt;context['postId'] );
	}

	if ( empty( $author_id ) ) {
		return '';
	}

	if ( isset( $block-&gt;context['postType'] ) &amp;&amp; ! post_type_supports( $block-&gt;context['postType'], 'author' ) ) {
		return '';
	}

	$avatar = ! empty( $attributes['avatarSize'] ) ? get_avatar(
		$author_id,
		$attributes['avatarSize']
	) : null;

	$link        = get_author_posts_url( $author_id );
	$author_name = get_the_author_meta( 'display_name', $author_id );
	if ( ! empty( $attributes['isLink'] &amp;&amp; ! empty( $attributes['linkTarget'] ) ) ) {
		$author_name = sprintf( '&lt;a href=&quot;%1$s&quot; target=&quot;%2$s&quot;&gt;%3$s&lt;/a&gt;', esc_url( $link ), esc_attr( $attributes['linkTarget'] ), $author_name );
	}

	$byline  = ! empty( $attributes['byline'] ) ? $attributes['byline'] : false;
	$classes = array();
	if ( isset( $attributes['itemsJustification'] ) ) {
		$classes[] = 'items-justified-' . $attributes['itemsJustification'];
	}
	if ( isset( $attributes['textAlign'] ) ) {
		$classes[] = 'has-text-align-' . $attributes['textAlign'];
	}
	if ( isset( $attributes['style']['elements']['link']['color']['text'] ) ) {
		$classes[] = 'has-link-color';
	}

	$wrapper_attributes = get_block_wrapper_attributes( array( 'class' =&gt; implode( ' ', $classes ) ) );

	return sprintf( '&lt;div %1$s&gt;', $wrapper_attributes ) .
	( ! empty( $attributes['showAvatar'] ) ? '&lt;div class=&quot;wp-block-post-author__avatar&quot;&gt;' . $avatar . '&lt;/div&gt;' : '' ) .
	'&lt;div class=&quot;wp-block-post-author__content&quot;&gt;' .
	( ! empty( $byline ) ? '&lt;p class=&quot;wp-block-post-author__byline&quot;&gt;' . wp_kses_post( $byline ) . '&lt;/p&gt;' : '' ) .
	'&lt;p class=&quot;wp-block-post-author__name&quot;&gt;' . $author_name . '&lt;/p&gt;' .
	( ! empty( $attributes['showBio'] ) ? '&lt;p class=&quot;wp-block-post-author__bio&quot;&gt;' . get_the_author_meta( 'user_description', $author_id ) . '&lt;/p&gt;' : '' ) .
	'&lt;/div&gt;' .
	'&lt;/div&gt;';
}

/**
 * Registers the `core/post-author` block on the server.
 *
 * @since 5.9.0
 */
function register_block_core_post_author() {
	register_block_type_from_metadata(
		__DIR__ . '/post-author',
		array(
			'render_callback' =&gt; 'render_block_core_post_author',
		)
	);
}
add_action( 'init', 'register_block_core_post_author' );
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