private static function checkout( $atts ) {

		// if there are membership restrictions, check the user is in at least one membership.
		// this is to combat CHEATERS.
		if ( $atts['plan']->has_availability_restrictions() ) {
			$access = false;
			foreach ( $atts['plan']->get_array( 'availability_restrictions' ) as $mid ) {

				// once we find a membership, exit.
				if ( llms_is_user_enrolled( self::$uid, $mid ) ) {
					$access = true;
					break;
				}
			}
			if ( ! $access ) {
				llms_print_notice( __( 'You must be a member in order to purchase this access plan.', 'lifterlms' ), 'error' );
				return;
			}
		}

		if ( self::$uid ) {
			// ensure the user isn't enrolled in the product being purchased.
			if ( isset( $atts['product'] ) && llms_is_user_enrolled( self::$uid, $atts['product']->get( 'id' ) ) ) {

				/**
				 * Filter the displaying of the checkout form notice for already enrolled in the product being purchased.
				 *
				 * @since 4.2.0
				 *
				 * @param bool $display_notice Whether or not displaying the checkout form notice for already enrolled students in the product being purchased.
				 */
				if ( apply_filters( 'llms_display_checkout_form_enrolled_students_notice', true ) ) {
					llms_print_notice(
						sprintf(
							// Translators: %2$s = The product type (course/membership); %1$s = product permalink.
							__( 'You already have access to this %2$s! Visit your dashboard <a href="%1$s">here.</a>', 'lifterlms' ),
							llms_get_page_url( 'myaccount' ),
							$atts['product']->get_post_type_label()
						),
						'notice'
					);
				}

				return;
			}

			$user = get_userdata( self::$uid );
			llms_print_notice( sprintf( __( 'You are currently logged in as <em>%1$s</em>. <a href="%2$s">Click here to logout</a>', 'lifterlms' ), $user->user_email, wp_logout_url( $atts['plan']->get_checkout_url() ) ), 'notice' );
		} else {
			llms_get_login_form( sprintf( __( 'Already have an account? <a href="%s">Click here to login</a>', 'lifterlms' ), '#llms-show-login' ), $atts['plan']->get_checkout_url() );
		}

		llms_get_template( 'checkout/form-checkout.php', $atts );

	}