code: def add_plugin_directories(self, paths, except_blacklisted=True):
          
          self.directory_manager.add_directories(paths, except_blacklisted)
docs: Adds `directories` to the set of plugin directories.
  
          `directories` may be either a single object or a iterable.
  
          `directories` can be relative paths, but will be converted into
          absolute paths based on the current working directory.
  
          if `except_blacklisted` is `True` all `directories` in
          that are blacklisted will be removed