Added by Jeremy Cline over 5 years ago
list_files() from FileContentUnit to ContentUnit.
list_files() method definition to ContentUnit. This is
convenient when receiving a list of ContentUnit derivatives that may or
may not have inherited from FileContentUnit. The default implementation
on ContentUnit returns an empty list unless
_storage_path is defined,
so a user can call
list_files on any ContentUnit subclass when dealing
with content files.