protected function get_tax_query() {

		$has_tax_query = false;

		$tax_query = array(
			'relation' => 'AND',
		);

		$category = $this->get_attribute( 'category' );
		if ( $category ) {
			$tax_query[]   = array(
				'taxonomy' => 'course_cat',
				'field'    => 'slug',
				'terms'    => $category,
			);
			$has_tax_query = true;
		}

		$hidden = $this->get_attribute( 'hidden' );
		if ( 'no' === $hidden ) {

			$terms = wp_list_pluck(
				get_terms(
					array(
						'taxonomy'   => 'llms_product_visibility',
						'hide_empty' => false,
					)
				),
				'term_taxonomy_id',
				'name'
			);

			$tax_query[]   = array(
				'field'    => 'term_taxonomy_id',
				'operator' => 'NOT IN',
				'taxonomy' => 'llms_product_visibility',
				'terms'    => array( $terms['hidden'] ),
			);
			$has_tax_query = true;
		}

		return $has_tax_query ? $tax_query : '';

	}