code: def fit(self, x, y=None):
      return self
  
imports: from sklearn.base import BaseEstimator, TransformerMixin
  import string
  from underthesea.pipeline.word_tokenize import tokenize
  from underthesea.utils.vietnamese_features import remove_tone
label_desc: Use image node_id 3 for calling the CountEmoticons obj's underlying member method code with example usage: obj.fit(x, y) and returns: self