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function set_posts_per_page_for_cpt( $query ) {
	if( !is_admin() and $query->is_main_query() )
	{
  		if ( is_post_type_archive( 'news' ) or is_tax( 'news-category' ) )
  		{
  			$news_posts_per_page = get_field( 'news_posts_per_page', 'option' );
    		$query->set( 'posts_per_page', $news_posts_per_page );
  		}
  	}
}
add_action( 'pre_get_posts', 'set_posts_per_page_for_cpt' );