class_docstr: Test that the correct answer is correct, and the rest are incorrect.
  
  The test is done by numerically evaluating expressions over a range
  of its variables, using exact rational aritmetic (the "fractions" module).
  
  (Used internally by ProblemGenerator, problem.py).
docstr: Receive the equation (the question) and the available answers,
  as generated by ProblemGenerator._generate.
docstr_tok: ["Receive","the","equation","(","the","question",")","and","the","available","answers",",","as","generated","by","ProblemGenerator._generate","."]
code: def __init__(self, eq, answers):
      """
      Receive the equation (the question) and the available answers,
      as generated by ProblemGenerator._generate.
      """
      self.question = Code(eq)
      self.answers = []
  
      for correct, answer in answers:
          if correct:
              self.correct = len(self.answers)
          self.answers.append(Code(answer))
  
file_path: evals/evals/registry/data/solve-for-variable/tools/tester.py
imports: import ast
  from fractions import Fraction
  from solve import EquationGenerator
label_desc: Use image node_id 1 to create a new Evaluator object  with example: obj = Evaluator(eq, answers)