WordPress at a glance
function is not described

Composer\Autoload

ClassLoader::set() public WC 1.0

Registers a set of PSR-0 directories for a given prefix, replacing any others previously set for this prefix.

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

No Hooks.

Return

null. Nothing.

Usage

$ClassLoader = new ClassLoader();
$ClassLoader->set( $prefix, $paths );
$prefix(string) (required)
The prefix
$paths(array|string) (required)
The PSR-0 base directories

Code of ClassLoader::set() WC 5.3.0

<?php
public function set($prefix, $paths)
{
    if (!$prefix) {
        $this->fallbackDirsPsr0 = (array) $paths;
    } else {
        $this->prefixesPsr0[$prefix[0]][$prefix] = (array) $paths;
    }
}