code: def fit(self, data_inputs, expected_outputs=None) -> "BaseStep":
      self._add_fitted_data(data_inputs, expected_outputs)
      return self
  
imports: import copy
  from typing import Any, Tuple
  import numpy
  import pytest
  from neuraxle.base import BaseStep
  from neuraxle.steps.column_transformer import ColumnTransformer
label_desc: Use image node_id 2 for calling the MultiplyBy2 obj's underlying member method code with example usage: obj.fit(data_inputs, expected_outputs) and returns: self