What is this function in php used for: stream_resolve_include_path

I saw this function was used to introduce certificates in the project:
stream_resolve_include_path($cfg['cainfo']

Reply content:

I saw this function was used to introduce certificates in the project:
stream_resolve_include_path($cfg['cainfo']

Complain: Don’t you check the manual when you encounter a function you don’t know how to use? --Please open http://php.net/manual/zh. There is a search in the upper right corner. Enter the function name you are looking for and then search.