WP_Rewrite::add_endpoint( string $name, int $places, string|bool $query_var = true )

1752	public function add_endpoint( $name, $places, $query_var = true ) {1753		global $wp;1754 1755		// For backward compatibility, if null has explicitly been passed as `$query_var`, assume `true`.1756		if ( true === $query_var || null === $query_var ) {1757			$query_var = $name;1758		}1759		$this->endpoints[] = array( $places, $name, $query_var );1760 1761		if ( $query_var ) {1762			$wp->add_query_var( $query_var );1763		}1764	}