Function load_rec_dir 

pub fn load_rec_dir<T: DirLoadable + Asset>(
    specifier: &str,
) -> Result<AssetDirHandle<T>, Error>

Loads directory and all files in it.

“rec” stands for “recursively”

Note, this only gets the ids of assets, they are not actually loaded. The returned handle can be used to iterate over the IDs or to iterate over assets trying to load them.

Errors

An error is returned if the given id does not match a valid readable directory.

When loading a directory recursively, directories that can’t be read are ignored.