CP2: bit_list_to_where_clause() definition?

Content

In the process of upgrading a site from CP2 to CP3, I've come across this function that is quite confusing. I'm not sure what the equivalent of it would be for CP3. The line says:

 // $accessLevels is a comma seperated string, eg: 8,12,33
$whereBit = bit_list_to_where_clause($accessLevels, "access_mask");

Any idea where I can see what that function does?

Version

3.7