code: def test_add(self):
      f, g = self.f, self.g
  
      self.check_constant_output(f + g, 5.0)
  
      self.check_constant_output((1 + f) + g, 6.0)
      self.check_constant_output(1 + (f + g), 6.0)
      self.check_constant_output((f + 1) + g, 6.0)
      self.check_constant_output(f + (1 + g), 6.0)
      self.check_constant_output((f + g) + 1, 6.0)
      self.check_constant_output(f + (g + 1), 6.0)
  
      self.check_constant_output((f + f) + f, 9.0)
      self.check_constant_output(f + (f + f), 9.0)
  
      self.check_constant_output((f + g) + f, 8.0)
      self.check_constant_output(f + (g + f), 8.0)
  
      self.check_constant_output((f + g) + (f + g), 10.0)
      self.check_constant_output((f + g) + (g + f), 10.0)
      self.check_constant_output((g + f) + (f + g), 10.0)
      self.check_constant_output((g + f) + (g + f), 10.0)
  
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 11 for calling the NumericalExpressionTestCase obj's underlying member method code with example usage: obj.test_add() without return types