code: def _verify_student_input(self, student_input, locked):
          
          guesses = [student_input]
          try:
              guesses.append(repr(ast.literal_eval(student_input)))
          except Exception:
              pass
          if student_input.title() in self.SPECIAL_INPUTS:
              guesses.append(student_input.title())
          for guess in guesses:
              if self._verify(guess, locked):
                  return guess
docs: If the student's answer is correct, returns the normalized answer.
          Otherwise, returns None.