code: def test_polynomial_variables(self):
      # The zero polynomial has no variables.
  
      self.assertEqual(self.p0.variables(), set())
      self.assertEqual(self.p1.variables(), set())
  
      # The total variables are the union of the variables
      # from the monomials.
      self.assertEqual(self.p4.variables(), {1, 2, 3})
  
      # The monomials with coefficient 0 should be dropped.
      self.assertEqual(self.p5.variables(), {1, 3})
      return
  
file_path: keon-algos/tests/test_polynomial.py
imports: from algorithms.maths.polynomial import Polynomial, Monomial
  from fractions import Fraction
  import math
  import unittest
label_desc: Use image node_id 6 for calling the TestSuite obj's underlying member method code with example usage: obj.test_polynomial_variables() without return types