examples/research_projects/longform-qa/eli5_utils.py/ELI5DatasetQARetriver/make_example
class ELI5DatasetQARetriver:    def make_example(self, idx):
        example = self.data[idx]
        question = example["title"]
        if self.training:
            answers = [a for i, (a, sc) in enumerate(zip(example["answers"]["text"], example["answers"]["score"]))]
            answer_tab = choice(answers).split(" ")
            start_idx = randint(0, max(0, len(answer_tab) - self.min_length))
            answer_span = " ".join(answer_tab[start_idx:])
        else:
            answer_span = example["answers"]["text"][0]
        return (question, answer_span)