code: def chi_square_calc(classes, table, TOP, P, POP):
      
      try:
          result = 0
          for i in classes:
              for index, j in enumerate(classes):
                  expected = (TOP[j] * P[i]) / (POP[i])
                  result += ((table[i][j] - expected)**2) / expected
          return result
      except Exception:
          return "None"
docs: Calculate chi-squared.
  
      :param classes: confusion matrix classes
      :type classes : list
      :param table: confusion matrix table
      :type table : dict
      :param TOP: test outcome positive
      :type TOP : dict
      :param P: condition positive
      :type P : dict
      :param POP: population
      :type POP : dict
      :return: chi-squared as float