class_docstr: FrequencyEncoder
  Conversion of category into frequencies.
  Parameters
      ----------
  cols : list of categorical features.
  drop_invariant : not used
docstr: Description of fit_transform
  
  Args:
      X (pd.DataFrame): dataset
      y=None (undefined): not used
  
  Returns:
      pd.DataFrame
docstr_tok: ["Description","of","fit_transform","Args",":","X","(","pd.DataFrame",")",":","dataset","y=None","(","undefined",")",":","not","used","Returns",":","pd.DataFrame"]
code: def fit_transform(self, X: pd.DataFrame, y=None) -> pd.DataFrame:
      """
      Description of fit_transform
  
      Args:
          X (pd.DataFrame): dataset
          y=None (undefined): not used
  
      Returns:
          pd.DataFrame
  
      """
      self.fit(X, y)
      X = self.transform(X)
      return X
  
imports: import pandas
  import numpy
label_desc: Use image node_id 4 for calling the FrequencyEncoder obj's underlying member method code with example usage: obj.fit_transform(X, y) and returns: X