code: def fit(self, X):
      X = self._fit_na_fill(X)
  
file_path: mljar-supervised/supervised/preprocessing/preprocessing_missing.py
imports: import json
  import os
  import numpy
  import pandas
  from supervised.preprocessing.preprocessing_utils import PreprocessingUtils
label_desc: Use image node_id 2 for calling the PreprocessingMissingValues obj's underlying member method code with example usage: obj.fit(X) without return types