docs: def generate(self, path, label):
          """Creates default data from the corpus at `path`, marking all
          works with `label`.
  
          :param path: path to a corpus directory
          :type path: `str`
          :param label: label to categorise each work as
          :type label: `str`
  
          """
          for filename in os.listdir(path):
              self[filename] = label