docs: def remove_directories(self, directories):
          """
          Removes any `directories` from the set of plugin directories.
  
          `directories` may be a single object or an iterable.
  
          Recommend passing in all paths as absolute, but the method will
          attemmpt to convert all paths to absolute if they are not already
          based on the current working directory.
          """
          directories = util.to_absolute_paths(directories)
          self.plugin_directories = util.remove_from_set(self.plugin_directories,
                                                         directories)