get_user_count() WordPress Function

function get_user_count( $network_id = null ) {
	if ( ! is_multisite() && null !== $network_id ) {
		_doing_it_wrong(
			__FUNCTION__,
			sprintf(
				/* translators: %s: $network_id */
				__( 'Unable to pass %s if not using multisite.' ),
				'<code>$network_id</code>'
			),
			'6.0.0'
		);
	}

	return (int) get_network_option( $network_id, 'user_count', -1 );
}