code: def test_subtract(self):
      f, g = self.f, self.g
  
      self.check_constant_output(f - g, 1.0)  # 3 - 2
  
      self.check_constant_output((1 - f) - g, -4.0)  # (1 - 3) - 2
      self.check_constant_output(1 - (f - g), 0.0)  # 1 - (3 - 2)
      self.check_constant_output((f - 1) - g, 0.0)  # (3 - 1) - 2
      self.check_constant_output(f - (1 - g), 4.0)  # 3 - (1 - 2)
      self.check_constant_output((f - g) - 1, 0.0)  # (3 - 2) - 1
      self.check_constant_output(f - (g - 1), 2.0)  # 3 - (2 - 1)
  
      self.check_constant_output((f - f) - f, -3.0)  # (3 - 3) - 3
      self.check_constant_output(f - (f - f), 3.0)  # 3 - (3 - 3)
  
      self.check_constant_output((f - g) - f, -2.0)  # (3 - 2) - 3
      self.check_constant_output(f - (g - f), 4.0)  # 3 - (2 - 3)
  
      self.check_constant_output(
          (f - g) - (f - g), 0.0
      )  # (3 - 2) - (3 - 2)
      self.check_constant_output(
          (f - g) - (g - f), 2.0
      )  # (3 - 2) - (2 - 3)
      self.check_constant_output(
          (g - f) - (f - g), -2.0
      )  # (2 - 3) - (3 - 2)
      self.check_constant_output((g - f) - (g - f), 0.0)
  
imports: from itertools import permutations
  from operator import add, ge, gt, le, lt, methodcaller, mul, ne, sub
  from string import ascii_uppercase
  from unittest import TestCase
  import numpy
  from numpy import arange, array, eye, float64, full, isnan, zeros
  from pandas import DataFrame, date_range, Int64Index
  from catalyst.pipeline import Factor, Filter
  from catalyst.pipeline.expression import NumericalExpression, NUMEXPR_MATH_FUNCS
  from catalyst.testing import check_allclose
  from catalyst.utils.numpy_utils import datetime64ns_dtype, float64_dtype
label_desc: Use image node_id 12 for calling the NumericalExpressionTestCase obj's underlying member method code with example usage: obj.test_subtract() without return types