code: def test_numerical(self):
      D = Differencer()
      D.fit(np.array([1, 2, 3]))
  
      reconstructed = D.inverse_transform(
          D.transform(np.array([4, 5, 6]))
      )
      target = pd.Series([3, 4, 5])
      self.assertTrue(reconstructed.all() == target.all())
  
      reconstructed = D.inverse_transform(
          D.transform(np.array([4, 5, 6])), init=4
      )
      target = pd.Series([4, 5, 6])
      self.assertTrue(reconstructed.all() == target.all())
  
imports: import unittest
  import numpy
  import pandas
  from lightwood.helpers.ts import Differencer
label_desc: Use image node_id 1 for calling the TestTSDifferencer obj's underlying member method code with example usage: obj.test_numerical() without return types