code: def remove_tone(self, s):
      return remove_tone(s)
  
imports: from sklearn.base import BaseEstimator, TransformerMixin
  import string
  import re
  from underthesea.pipeline.word_tokenize import tokenize
  from underthesea.utils.vietnamese_features import remove_tone
label_desc: Use image node_id 1 for calling the RemoveTone obj's underlying member method code with example usage: obj.remove_tone(s) and returns: remove_tone