code: def remove_by_threshold(self, threshold=5):
          
          keys = [x for x in self._dictionary.keys()]
          for key in keys:
              if self._dictionary[key] <= threshold:
                  self._dictionary.pop(key)
          self._update_dictionary()
docs: Remove all words at, or below, the provided threshold
  
              Args:
                  threshold (int): The threshold at which a word is to be \
                  removed