WMPU DEV display a random post from each category

code_full.php

<section class="random>">
	
	<?php
	
	$terms = get_terms( array( 
		'taxonomy' => 'category',
		'parent'   => 0
	) );
	
	$do_not_duplicate = array();
	
	if ( $terms ) {
		
		echo '<h3>Random Content</h3>';
		echo '<ul class ="randomposts">';
		
			foreach( $terms as $term ) {	
			
				// define the arguments
				$args = array(
					'post_type' => 'post',
					'orderby' => 'rand',
					'posts_per_page' => 1,
					'post__not_in' => $do_not_duplicate,
					'tax_query' => array(
						array(
							'taxonomy' => 'category',
							'field'    => 'slug',
							'terms'    => $term,
						),
					),
				);
				
				// run the query
				$query = new WP_query ( $args );
				
				if ( $query->have_posts() ) {
					
					while ( $query->have_posts() ) : $query->the_post();
					
						echo '<li>' . $term->name . ': <a href=' . get_the_permalink() . '">' . get_the_title() . '</a></h3>';
						$do_not_duplicate[] = $post->ID;
											
					endwhile;
					rewind_posts();
					
				}
				
			}
			
		echo '</ul>';
		
	}			
	?>	
	
</section>

do_not_duplicate_add.php

$do_not_duplicate[] = $post->ID;

do_not_duplicate_arg.php

$args = array(
	'post_type' => 'post',
	'orderby' => 'rand',
	'posts_per_page' => 1,
	'post__not_in' => $do_not_duplicate,
	'tax_query' => array(
		array(
			'taxonomy' => 'category',
			'field'    => 'slug',
			'terms'    => $term,
		),
	),
);

do_not_duplicate_array.php

$do_not_duplicate = array();

get_terms.php

<?php

$terms = get_terms( array( 
	'taxonomy' => 'category',
	'parent'   => 0
) );

if ( $terms ) {
		
	echo '<h3>Random Content</h3>';
	echo '<ul class ="randomposts">';
		
		foreach( $terms as $term ) {	

		}

}	
?>	

run_query.php

// run the query
$query = new WP_query ( $args );

if ( $query->have_posts() ) {
	
	while ( $query->have_posts() ) : $query->the_post();
	
		echo '<li>' . $term->name . ': <a href=' . get_the_permalink() . '">' . get_the_title() . '</a></h3>';
							
	endwhile;
	rewind_posts();
	
}

wp_query.php

$args = array(
  'post_type' => 'post',
  'orderby' => 'rand',
  'posts_per_page' => 1,
  'tax_query' => array(
    array(
      'taxonomy' => 'category',
      'field'    => 'slug',
      'terms'    => $term,
    ),
 )
);