docstr: fit transform should give the same result as calling fit and
  transform separately
code: def test_fit_transform(self):
      """fit transform should give the same result as calling fit and
      transform separately"""
  
      arr = np.array([n + 1 for n in range(10)])
      np.random.shuffle(arr)
  
      d1 = Discretiser(method="outlier", outlier_percentile=0.2)
      d1.fit(arr)
      r1 = d1.transform(arr)
  
      d2 = Discretiser(method="outlier", outlier_percentile=0.2)
      r2 = d2.fit_transform(arr)
  
      assert np.array_equal(r1, r2)
  
imports: import math
  import numpy
  import pytest
  from causalnex.discretiser import Discretiser
label_desc: Use image node_id 6 for calling the TestOutlier obj's underlying member method code with example usage: obj.test_fit_transform() without return types