Only allow 1 access token session per client

only one access_token session

/**
 * Only allow 1 acces_token at a time
 * @param  [type] $results [description]
 * @return [type]          [description]
 */
function test_only_allow_one_access_token ( $object ) {
	if ( is_null( $object ) ) 
		return;

	// Define the user ID
	$user_id = $object['user_id'];

	// Remove all other access tokens and refresh tokens from the system
	global $wpdb;
	$wpdb->delete( "{$wpdb->prefix}oauth_access_tokens", array( "user_id" => $user_id ) );
	$wpdb->delete( "{$wpdb->prefix}oauth_refresh_tokens", array( "user_id" => $user_id) );

	return;
}
add_action('wo_set_access_token', 'test_only_allow_one_access_token');