get_the_category() experiment

<?php
/*
Plugin Name: get_the_category experiment
Plugin URI: https://www.damiencarbery.com
Description: Experiment with get_the_category() function.
Author: Damien Carbery
Version: 0.1
*/

add_filter( 'the_content', 'append_get_the_category' );
function append_get_the_category( $content ) {
	if ( !is_single() ) return $content;

	$post_categories = get_the_category();

	$categories = array();
	foreach ( $post_categories as $category ) {
		$categories[] = sprintf( '<a href="%s" class="cat-%s">%s</a>', esc_url( get_category_link( $category->term_id ) ), $category->slug, $category->name );
	}
	return $content . implode( ' ', $categories );
}

/*
WP_Term::__set_state(array(
     'term_id' => 24,
     'name' => 'Foo Parent',
     'slug' => 'foo-parent',
     'term_group' => 0,
     'term_taxonomy_id' => 24,
     'taxonomy' => 'category',
     'description' => '',
     'parent' => 0,
     'count' => 1,
     'filter' => 'raw',
     'cat_ID' => 24,
     'category_count' => 1,
     'category_description' => '',
     'cat_name' => 'Foo Parent',
     'category_nicename' => 'foo-parent',
     'category_parent' => 0,
  )),*/