WordPress at a glance
function is not described

wp_atom_server::__call() public WP 1.0

It's a method of the class: wp_atom_server{}

No Hooks.

Return

Null. Nothing.

Usage

$wp_atom_server = new wp_atom_server();
$wp_atom_server->__call( $name, $arguments );

Code of wp_atom_server::__call() WP 5.5.1

<?php
public function __call( $name, $arguments ) {
	_deprecated_function( __CLASS__ . '::' . $name, '3.5.0', 'the Atom Publishing Protocol plugin' );
}