nested

$tax_query = array(
	'relation' => 'AND',
	array(
		array(
			'taxonomy'         => 'post_tag',
			'terms'            => array( 'pro', 'plus' ),
			'field'            => 'slug',
		),
	),
	array(
		array(
			'taxonomy'         => 'post_tag',
			'terms'            => 'plus',
			'field'            => 'slug',
		),
	),
	array(
		array(
			'taxonomy'         => 'post_tag',
			'terms'            => 'basic',
			'field'            => 'slug',
		),
	),
);